How does that account for the fact that the mini will be the very device sending said video to AppleTV?
Good thing it has those two processors to do the video decoding.
Actually thing about this further this is intended for PC's also. And the PC world is rife with integrated video with even less capability than GMA 950. Apple does not list a limit for computers capable of working with AppleTV.
Both these statements indicate that you don't really understand what you're talking about.
For the first comment: How does a Mac Mini's video output quality affect the data that it will send to the AppleTV? How does it affect the quality of output from the AppleTV? The answer to both these questions is that it doesn't. The Mini sends compressed video data (a raw H.264 data stream, for example), and the AppleTV decompresses this data and displays it on a screen. The GMA950 in the Mac Mini is not involved in this process in any way.
For the second: Yes, there is the possibility of Apple implementing in software (on a Mac Mini) all those features that would provide for decent video quality (output direct from a Mac Mini). Shame they don't do that, isn't it?
If you were change that statement to I don't don't understand what you (Mr. H) are talking about. Then I would agree.
If you don't understand the basics of video decompression, which factors will - and which factors won't - affect picture quality, why did you start this debate with me?
"To say that Apple TV is the world's best media streaming device could be considered faint praise, the tech equivalent of calling someone the world's tallest midget," Albro said. "After all, most previous versions of these devices, which take music, video, and photos from your PC and play them on your TV and stereo, have been unreliable, hard to use and generally shunned by the buying public."
taking away praise because the competitors are hopeless ??
you could draw the same comparison to the ipod and its competitors, and look how it changed the way we buy and use music/movies/tv shows/games etc, and both use itunes,
That may be true but it seems to me you keep changing the coversation.
Your first statement was responding to someone complaining that people should just buy a Mac mini. You said quality should be paramount. My resopnce was that there needs to be compromise in quality for convenience.
Then you go on talk about AppleTV output being higher than the Mac mini because of the GPU. Exactly what content is available that AppleTV will play that the Mac mini won't?
Then you go on to say Mac mini only needs to stream content to AppleTV and that the GPU does not matter. As though there will be no option for people to watch the content they will be streaming. My question is what content is this?
So yes I am lost. It seems you are saying I don't know enough to even have this discussion. That may be true. But I think you are making it more complicated than it really is.
That may be true but it seems to me you keep changing the coversation.
Your first statement was responding to someone complaining that people should just buy a Mac mini. You said quality should be paramount. My resopnce was that there needs to be compromise in quality for convenience.
Then you go on talk about AppleTV output being higher than the Mac mini because of the GPU. Exactly what content is available that AppleTV will play that the Mac mini won't?
Then you go on to say Mac mini only needs to stream content to AppleTV and that the GPU does not matter. As though there will be no option for people to watch the content they will be streaming. My question is what content is this?
So yes I am lost. It seems you are saying I don't know enough to even have this discussion. That may be true. But I think you are making it more complicated than it really is.
I may be wrong about how the AppleTV works, but I believe the Mac Mini or PC or whatever computer doesn't do anything with the video file you want to play on the AppleTV. It's just acting as a file server, sending the original .m4v file to the AppleTV. The Mac Mini doesn't decode the video or do any sort of processing (except perhaps validating that you are authorized to view it before it allows the transfer). This is why the only specs required for the computer is the ability to run iTunes 7.1.
All the decoding happens on the AppleTV. Since the AppleTV has a better GPU than the Mini it can apply advanced video processing to the decoded video and thus provide a better picture than the Mac Mini could.
We went through this with the HD also. When Disney CEO Iger first said there was a HD. Because Apple had not publicly stated that AppleTV would have an HD many people assumed it was speculation at best and he did not know what he was talking about at worst.
What's likely the truth is that Apple told Iger it had an HD and Apple told Mossberg that it runs OS X, they both publicly stated what Apple had told them, only Apple had not yet publicly confirmed either.
Ayup, agreed, and neither said "I have it on good authority..." or "According to my sources...", either of which would have pretty much stated clearly what was going on, and in a way that still left the details appropriately vague. Iger I understand, his was on off the cuff comment, but Mossberg surprised me on this one.
OTOH, while he offered no evidence, and just threw it out there, it always amazes me that people will polarize over such a silly thing. "See!? Confirmed!" vs. "He's wild-assed guessing, and is wrong, I just know it." Without supporting evidence, even the vague kind, people read what they want to, unfortunately. All it means is that it's an unsubstantiated assertion, and needs further evidence from somewhere to confirm or deny. It means nothing about the author's sources or lack thereof, because they don't give any hints about that. Flipping a coin, if lucky, gives the same result as confirmed documents countersigned by Jobs himself. It also means nothing about whether they are accurate or not, they may be dead-on, but who knows without evidence?
In any case, it's all pretty silly to get one's panties in a bunch over. I mean hell, a couple days later we had confirmation, and Mossberg's vagueness is completely irrelevant.
If you don't understand the basics of video decompression, which factors will - and which factors won't - affect picture quality, why did you start this debate with me?
Mr. H, just speaking for myself, I do find you a tad incomprhensible, and full of yourself!
Either answer a simple question (if someone wants to know when you choose to post a view), or please shut up.
Your knowledge is no good unless shared, and your seemingly thin skin does not help.
PS: Your reponse was not to my post.... I am just p-o'ed at your arrogance, that's all.
I may be wrong about how the AppleTV works, but I believe the Mac Mini or PC or whatever computer doesn't do anything with the video file you want to play on the AppleTV. It's just acting as a file server, sending the original .m4v file to the AppleTV. The Mac Mini doesn't decode the video or do any sort of processing (except perhaps validating that you are authorized to view it before it allows the transfer). This is why the only specs required for the computer is the ability to run iTunes 7.1.
All the decoding happens on the AppleTV. Since the AppleTV has a better GPU than the Mini it can apply advanced video processing to the decoded video and thus provide a better picture than the Mac Mini could.
I hope this clears things up.
I realize that you are trying to be helpful, but it does not "clear things up" (sic).
For starters, what's 'GPU'? What does "Mac Mini doesn't decode the video or do any sort of processing" mean (and why is that different from what other Macs do or do not do)? And, what does "perhaps validating that you are authorized to view it before it allows the transfer" mean?
I could go on....
I think there's the beginnings of a problem with Apple when its apologists (I mean, aficionados) start to sound like a bunch of Windows fanatics who have way too much involvement with the technology to care about what it all actually means to users!
Wait... do you want us to share knowledge, or not? I'm confused. If we don't, it's no good, but if we do, we're out of touch with what users want. Eh?
Translation: the computer that has your files can be a low-powered one, and the AppleTV will work. The speed of the network is the most important part. The Mac mini will be fine as a host for the AppleTV. Better?
Oh crap. Look at this massive can of worms I opened! I hope I can explain it better for the likes of Tenobell and anantksundaram. Unfortunately, I fear that this is unlikely, since the issues are highly complex and to explain it all from the basics upwards requires a book, not a forum post.
First let me try and give a simple overview of the video playback process, and then I'll review the exchanges I had with Tenobell.
Video tracks have several parameters, four important ones are:
Resolution
Frame rate
Bit rate
Codec
I'm going to have to assume that you understand the basics of the first three, as I don't have time to go over them in depth. Let's talk about codecs.
Codecs are all about reducing the amount of space-required-to-store/bandwidth-required-to-transmit a video. Uncompressed video can be quite huge. Take a 24 bits per pixel (that's 8 bits each for red, green and blue) 1280 x 720 resolution video at 24 frames per second as an example. How many bits per second are required to represent this?
Each frame has 1280 x 720 = 921,600 pixels.
Each pixel has 24 bits of colour information = 22,118,400 bits per frame
There are 24 frames per second = 530,841,600 bits per second, i.e. approximately 531 Mbps or over 13 times the maximum data rate allowed on a blu-ray disc, to put it into some sort of context. 100 minutes (a common length for a movie) of such uncompressed data would require 371 GiB of data storage!
So, for practical purposes, we really need to radically reduce the amount of space required to store this file. Using lossless compression - whereby redundant data is removed for storage, but this data can be re-calculated from what's left such that the original file can be re-created perfectly, bit for bit - we can halve the amount of data required. This isn't nearly enough. We need a radical reduction. And that's what lossy codecs such as MPEG-2 and H.264 are for. The AppleTV will support H.264 at a maximum of 5 Mbps. Hopefully you can appreciate that achieving a compression ratio of over 100:1 and still maintaining a high-quality picture is not at all trivial. The codec specifies how the information should be removed from the original file, giving us a resultant H.264 stream. The codec also specifies how this data should then be decompressed to give us our picture information as displayed on screen.
Now, here's an important bit: since both compression and decompression are extremely complex, despite the fact that codec standards specify how a stream should be structured, the methods that should be used to generate such compressed streams from uncompressed streams, and the methods to decode the compressed streams, there is a lot of "wiggle-room" in implementations - especially on the de-code side there's a whole host of post-decompression filtering that you can perform, but don't have to, in order to try and improve the final picture quality. In other words, not all H.264 implementations are identical. Whilst on the encode side they'll all give you H.264 compliant-streams, and on the de-code side will all decode H.264 compliant streams, they won't all give you the same picture quality.
Next up is interlacing: interlacing is the process of dividing the picture up into odd and even lines. If the camera is an interlacing camera, even lines are captured, then odd lines are captured. The discussion of why you might want to do this is not important. Years ago, cameras were interlacing and TV sets were interlacing. Capture and playback methods matched up to one another.
Most modern forms of capturing and playing-back content don't use interlacing.
If you've got some interlaced content and need to display it on an LCD, plasma or DLP projector, you need to de-interlace it first. Simple you say: just take the one set of even lines, and the immediate next set of odd lines, and display them at the same time. Yes, you can do that, but it'll look rubbish. Why? Because the even and odd lines weren't captured at the same time, so if the subject and camera where moving relative to one another, there will be motion-related problems. Now, you can use loads of wicked-clever maths to overcome this problem (motion-compensated de-interlacing) and deliver a pretty damn good picture.
Next up, scaling: Imagine you've got a 640 x 360 pixel iTunes movie file, and your TV has 1360 x 768 pixels (a very common resolution for LCD tvs). How do you get your video to fill the screen completely, without having to crop it? On the horizontal scale, you've got 2.125 pixels on screen for each 1 pixel in the file, and on the vertical scale, you've got 2.133 pixels on screen for each 1 pixel in the file. Let's consider a single pixel in the very top left of the source file. Let's say it's coloured red. Which pixels on the screen should be coloured red? What's .125 of a pixel? .133 of a pixel? Again - here is where some clever maths is required to achieve optimal picture quality.
Now, let's review the process of playing back a file that contains an H.264 compressed video track - a stream of bits in an H.264-complaint structure that represents moving pictures:
Decode H.264
De-interlace (if the source is interlaced)
Scale (if source resolution and display resolution don't match)
Send data to screen
The AppleTV can do all these things. Each stage can contribute to the final picture quality achieved. The GeForce 7300 go can do all of these things in hardware, and it does it very well.
With the Mac Mini, the GMA950 can do the de-interlacing and scaling in hardware, but it does it very poorly. You can do de-interlacing and scaling in software running on the Core2Duo processors, but the QuickTime de-interlacing and scaling isn't that good.
So, both AppleTV and Mac Mini have the potential to deliver top-notch picture quality, but it's much easier to achieve with the AppleTV since the hardware has all the functionality built-in already, it just needs relatively simple software (relative to the complex software-implementation of high-quality motion-compensated de-interlacing and scaling) to support those features.
For MPEG-4 content played on the AppleTV, the Geforce Go features are used, delivering superior picture quality relative to a Mac Mini. Using QuickTime plugins on the AppleTV however, all decoding, de-interlacing and scaling is performed on the CPU so will deliver equal performance to a Mac Mini. However, there is the potential there for Apple to deliver MPEG-2 and other codec support using some or all (depending on the codec in question) of the GeForce Go advanced features.
It is worth noting that most content won't be interlaced so the interlace performance might not matter all that much. I'm sure iTunes store files aren't interlaced, for example. It is also worth noting that interlaced content can be de-interlaced before being encoded. For example, a cable TV transmission may be interlaced. If you record this with a cable box, assuming the cable box doesn't do anything clever, you'll have an interlaced file. If you want to convert this file to H.264, you can as part of the process de-interlace the file before it's compressed. The quality of the algorithm used to de-interlace will affect the final picture quality of the file when it's played back; any de-interlacer in the playback hardware won't be needed and will therefore have no bearing on the final picture quality (but the H.264 decoder and scaling (if required) implementation will).
Having said all that Tenobell, here is the sequence of events in this thread from my point of view, with further expansion of each of the points I made:
Kip Kap Sol said people hacking the AppleTV might as well use a Mac Mini instead (i.e. - connect a Mac Mini to their TV, not an AppleTV to their TV)
I suggested that the AppleTV has superior video quality output than the Mac Mini. Whilst the Mac Mini has many advantages over an AppleTV in terms of range of capabilities, the AppleTV has superior video-playback hardware and therefore the potential for higher video output quality compared to a Mac Mini.
Then you said something along the lines of decent streaming performance and decent video output quality being mutually exclusive. I replied with a post pointing out that this is nonsense. Whether something is being streamed or read from HDD has no bearing on the quality of codec decoder, de-interlacer and scaler being used.
As long as the average bit-rate of the video being streamed is below the average throughput of the network over which it is being streamed, and the receiving device has a big enough buffer, there is no problem. Since the AppleTV will only go up to 720p and has 802.11n, and a 40 GB HDD (i.e. easily enough room for a, say, 20 second buffer), video bit-rate is not a problem in the context of streaming.
Then you made a post suggesting that if a Mac Mini is streaming to an AppleTV, the limiting factor will be the Mac Mini. In addition, you suggested that since the Mac Mini has a powerful Core2Duo processor, it doesn't matter that it has a GMA950 with rubbish video features.
I replied that your first point makes no sense (video output quality of a Mac Mini doesn't affect the video output quality of an AppleTV - the Mac Mini is sending a compressed video stream to the AppleTV, the Mac Mini is not modifying this stream in any way - it is the AppleTV that decodes the stream and displays the video) and that the second point could make sense but unfortunately Apple don't do all the things they'd need to do in software that the GMA doesn't do in hardware (and the Geforce 7300 does do in harware) to deliver maximum-quality pictures.
Wait... do you want us to share knowledge, or not? I'm confused.
You sound pretty smart, so I am surprised you are confused. Getting to the point, the answer is, yes, if you can manage to lose the snarkiness. O/w, I'll humbly repeat, shut up.
Quote:
Originally Posted by Kickaha
If we don't, it's no good, but if we do, we're out of touch with what users want. Eh?
And, if you don't, it's not necessarily "no good." We heathens will survive. (Btw, Canadian, eh?)
Quote:
Originally Posted by Kickaha
Translation: the computer that has your files can be a low-powered one, and the AppleTV will work. The speed of the network is the most important part. The Mac mini will be fine as a host for the AppleTV. Better?
No. (But thanks for the attempt at translation, despite it seeming to contradict other responses to the Mac Mini question).
You sound pretty smart, so I am surprised you are confused. Getting to the point, the answer is, yes, if you can manage to lose the snarkiness. O/w, I'll humbly repeat, shut up.
And, if you don't, it's not necessarily "no good." We heathens will survive. (Btw, Canadian, eh?)
No. (But thanks for the attempt at translation, despite it seeming to contradict other responses to the Mac Mini question).
Now, get back to your soldering.
anantksundaram, it is you that is being rude here, not me or Kickaha.
FYI, Kickaha is a programmer, not a hardware engineer. As far as I can tell, he really knows what he's doing. Most programmers of that capability that I know don't really like dealing with hardware so I imagine he doesn't play with a soldering iron all that much
The point remains that it seems odd to dispute a comment that someone makes if you don't really understand what's going on. You will note that Tenobell exchanged a few posts with me before he said he didn't understand what I was saying. Would it not have been a better idea for him to have said straight from the off he didn't get what I was saying, and to seek clarification? Instead he argued with me and proved in the process he doesn't understand the basics of video encoding, decoding and playback.
Oh crap. Look at this massive can of worms I opened! ...... to deliver maximum-quality pictures. (With a million or so words in-between I snipped)
Wow. Thanks. That was quite **phenomenal** by way of an explanation.
Yet, it does intrigue me that your say "So, both AppleTV and Mac Mini have the potential to deliver top-notch picture quality, but it's much easier to achieve with the AppleTV ....", a somewhat more hedged statement than the one prior. (In fairness, you do go on to explain the statement).
anantksundaram, it is you that is being rude here, not me or Kickaha.
FYI, Kickaha is a programmer, not a hardware engineer. As far as I can tell, he really knows what he's doing. Most programmers of that capability that I know don't really like dealing with hardware so I imagine he doesn't play with a soldering iron all that much
The point remains that it seems odd to dispute a comment that someone makes if you don't really understand what's going on. You will note that Tenobell exchanged a few posts with me before he said he did understand what I was saying. Would it not have been a better idea for him to have said straight from the off he didn't get what I was saying, and to seek clarification? Instead he argued with me and proved in the process he doesn't understand the basics of video encoding, decoding and playback.
Look, I honestly did not mean to be rude. (See above, which I replied to before your response to my response to Kickaha). I apologize for sounding ticked off.
My point is simple, and by now, should perhaps be obvious: Forums like these have as members that float in and out, that are young and old (posts-wise), are novices and pros (on a given issue). The fact that someone is "in," "old" and "pro" (or any other combination) has zero bearing.
No one is required to respond to anything.
There are a million forums like this, but I signed on to (and bother to stay involved with) AI only because I saw that AI seemed a little different, and actually, a bit more mature than the rest.
I have no problem at all being called on something. I expect that most people who post here -- regardless of vintage, knowledge, etc -- would feel the same way. (If that's not the case, I realize that one can simply pack up and leave).
Look, I honestly did not mean to be rude. (See above, which I replied to before your response to my response to Kickaha). I apologize for sounding ticked off.
My point is simple, and by now, should perhaps be obvious: Forums like these have as members that float in and out, that are young and old (posts-wise), are novices and pros (on a given issue). The fact that someone is "in," "old" and "pro" (or any other combination) has zero bearing.
No one is required to respond to anything.
There are a million forums like this, but I signed on to (and bother to stay involved with) AI only because I saw that AI seemed a little different, and actually, a bit more mature than the rest.
I have no problem at all being called on something. I expect that most people who post here -- regardless of vintage, knowledge, etc -- would feel the same way. (If that's not the case, I realize that one can simply pack up and leave).
Thank you for your post. I in turn apologise for rubbing you up the wrong way. It's 04:35 AM here so I really should have gone to bed hours ago! I would agree with you that on the whole, AI forums tend to be more balanced and mature with fewer flame-fests than other boards.
Comments
How does that account for the fact that the mini will be the very device sending said video to AppleTV?
Good thing it has those two processors to do the video decoding.
Actually thing about this further this is intended for PC's also. And the PC world is rife with integrated video with even less capability than GMA 950. Apple does not list a limit for computers capable of working with AppleTV.
Both these statements indicate that you don't really understand what you're talking about.
For the first comment: How does a Mac Mini's video output quality affect the data that it will send to the AppleTV? How does it affect the quality of output from the AppleTV? The answer to both these questions is that it doesn't. The Mini sends compressed video data (a raw H.264 data stream, for example), and the AppleTV decompresses this data and displays it on a screen. The GMA950 in the Mac Mini is not involved in this process in any way.
For the second: Yes, there is the possibility of Apple implementing in software (on a Mac Mini) all those features that would provide for decent video quality (output direct from a Mac Mini). Shame they don't do that, isn't it?
Both these statements indicate that you don't really understand what you're talking about.
If you were change that statement to I don't don't understand what you (Mr. H) are talking about. Then I would agree.
If you were change that statement to I don't don't understand what you (Mr. H) are talking about. Then I would agree.
If you don't understand the basics of video decompression, which factors will - and which factors won't - affect picture quality, why did you start this debate with me?
"To say that Apple TV is the world's best media streaming device could be considered faint praise, the tech equivalent of calling someone the world's tallest midget," Albro said. "After all, most previous versions of these devices, which take music, video, and photos from your PC and play them on your TV and stereo, have been unreliable, hard to use and generally shunned by the buying public."
you could draw the same comparison to the ipod and its competitors, and look how it changed the way we buy and use music/movies/tv shows/games etc, and both use itunes,
Your first statement was responding to someone complaining that people should just buy a Mac mini. You said quality should be paramount. My resopnce was that there needs to be compromise in quality for convenience.
Then you go on talk about AppleTV output being higher than the Mac mini because of the GPU. Exactly what content is available that AppleTV will play that the Mac mini won't?
Then you go on to say Mac mini only needs to stream content to AppleTV and that the GPU does not matter. As though there will be no option for people to watch the content they will be streaming. My question is what content is this?
So yes I am lost. It seems you are saying I don't know enough to even have this discussion. That may be true. But I think you are making it more complicated than it really is.
?and have significantly worse picture quality. I'd suggest that picture quality on a video-playing device should be a priority.
Can you explain what the issue with picture quality would be with a Mac Mini.... (I am asking this as a novice, not being argumentative).
That may be true but it seems to me you keep changing the coversation.
Your first statement was responding to someone complaining that people should just buy a Mac mini. You said quality should be paramount. My resopnce was that there needs to be compromise in quality for convenience.
Then you go on talk about AppleTV output being higher than the Mac mini because of the GPU. Exactly what content is available that AppleTV will play that the Mac mini won't?
Then you go on to say Mac mini only needs to stream content to AppleTV and that the GPU does not matter. As though there will be no option for people to watch the content they will be streaming. My question is what content is this?
So yes I am lost. It seems you are saying I don't know enough to even have this discussion. That may be true. But I think you are making it more complicated than it really is.
I may be wrong about how the AppleTV works, but I believe the Mac Mini or PC or whatever computer doesn't do anything with the video file you want to play on the AppleTV. It's just acting as a file server, sending the original .m4v file to the AppleTV. The Mac Mini doesn't decode the video or do any sort of processing (except perhaps validating that you are authorized to view it before it allows the transfer). This is why the only specs required for the computer is the ability to run iTunes 7.1.
All the decoding happens on the AppleTV. Since the AppleTV has a better GPU than the Mini it can apply advanced video processing to the decoded video and thus provide a better picture than the Mac Mini could.
I hope this clears things up.
I was suggesting to *really* mod the Mac Mini and route the wire outside.
For the mac mini that's been done I've seen that a few times. I thought you were talking about appleTV
If you take an Apple TV with an upgraded HD into a store, will they refuse to fix it?
Why you wouldnt want to do that can be summed up in three words
Whole unit replacement
We went through this with the HD also. When Disney CEO Iger first said there was a HD. Because Apple had not publicly stated that AppleTV would have an HD many people assumed it was speculation at best and he did not know what he was talking about at worst.
What's likely the truth is that Apple told Iger it had an HD and Apple told Mossberg that it runs OS X, they both publicly stated what Apple had told them, only Apple had not yet publicly confirmed either.
Ayup, agreed, and neither said "I have it on good authority..." or "According to my sources...", either of which would have pretty much stated clearly what was going on, and in a way that still left the details appropriately vague. Iger I understand, his was on off the cuff comment, but Mossberg surprised me on this one.
OTOH, while he offered no evidence, and just threw it out there, it always amazes me that people will polarize over such a silly thing. "See!? Confirmed!" vs. "He's wild-assed guessing, and is wrong, I just know it." Without supporting evidence, even the vague kind, people read what they want to, unfortunately. All it means is that it's an unsubstantiated assertion, and needs further evidence from somewhere to confirm or deny. It means nothing about the author's sources or lack thereof, because they don't give any hints about that. Flipping a coin, if lucky, gives the same result as confirmed documents countersigned by Jobs himself. It also means nothing about whether they are accurate or not, they may be dead-on, but who knows without evidence?
In any case, it's all pretty silly to get one's panties in a bunch over. I mean hell, a couple days later we had confirmation, and Mossberg's vagueness is completely irrelevant.
If you don't understand the basics of video decompression, which factors will - and which factors won't - affect picture quality, why did you start this debate with me?
Mr. H, just speaking for myself, I do find you a tad incomprhensible, and full of yourself!
Either answer a simple question (if someone wants to know when you choose to post a view), or please shut up.
Your knowledge is no good unless shared, and your seemingly thin skin does not help.
PS: Your reponse was not to my post.... I am just p-o'ed at your arrogance, that's all.
I may be wrong about how the AppleTV works, but I believe the Mac Mini or PC or whatever computer doesn't do anything with the video file you want to play on the AppleTV. It's just acting as a file server, sending the original .m4v file to the AppleTV. The Mac Mini doesn't decode the video or do any sort of processing (except perhaps validating that you are authorized to view it before it allows the transfer). This is why the only specs required for the computer is the ability to run iTunes 7.1.
All the decoding happens on the AppleTV. Since the AppleTV has a better GPU than the Mini it can apply advanced video processing to the decoded video and thus provide a better picture than the Mac Mini could.
I hope this clears things up.
I realize that you are trying to be helpful, but it does not "clear things up" (sic).
For starters, what's 'GPU'? What does "Mac Mini doesn't decode the video or do any sort of processing" mean (and why is that different from what other Macs do or do not do)? And, what does "perhaps validating that you are authorized to view it before it allows the transfer" mean?
I could go on....
I think there's the beginnings of a problem with Apple when its apologists (I mean, aficionados) start to sound like a bunch of Windows fanatics who have way too much involvement with the technology to care about what it all actually means to users!
Translation: the computer that has your files can be a low-powered one, and the AppleTV will work. The speed of the network is the most important part. The Mac mini will be fine as a host for the AppleTV. Better?
First let me try and give a simple overview of the video playback process, and then I'll review the exchanges I had with Tenobell.
Video tracks have several parameters, four important ones are:
- Resolution
- Frame rate
- Bit rate
- Codec
I'm going to have to assume that you understand the basics of the first three, as I don't have time to go over them in depth. Let's talk about codecs.Codecs are all about reducing the amount of space-required-to-store/bandwidth-required-to-transmit a video. Uncompressed video can be quite huge. Take a 24 bits per pixel (that's 8 bits each for red, green and blue) 1280 x 720 resolution video at 24 frames per second as an example. How many bits per second are required to represent this?
Each frame has 1280 x 720 = 921,600 pixels.
Each pixel has 24 bits of colour information = 22,118,400 bits per frame
There are 24 frames per second = 530,841,600 bits per second, i.e. approximately 531 Mbps or over 13 times the maximum data rate allowed on a blu-ray disc, to put it into some sort of context. 100 minutes (a common length for a movie) of such uncompressed data would require 371 GiB of data storage!
So, for practical purposes, we really need to radically reduce the amount of space required to store this file. Using lossless compression - whereby redundant data is removed for storage, but this data can be re-calculated from what's left such that the original file can be re-created perfectly, bit for bit - we can halve the amount of data required. This isn't nearly enough. We need a radical reduction. And that's what lossy codecs such as MPEG-2 and H.264 are for. The AppleTV will support H.264 at a maximum of 5 Mbps. Hopefully you can appreciate that achieving a compression ratio of over 100:1 and still maintaining a high-quality picture is not at all trivial. The codec specifies how the information should be removed from the original file, giving us a resultant H.264 stream. The codec also specifies how this data should then be decompressed to give us our picture information as displayed on screen.
Now, here's an important bit: since both compression and decompression are extremely complex, despite the fact that codec standards specify how a stream should be structured, the methods that should be used to generate such compressed streams from uncompressed streams, and the methods to decode the compressed streams, there is a lot of "wiggle-room" in implementations - especially on the de-code side there's a whole host of post-decompression filtering that you can perform, but don't have to, in order to try and improve the final picture quality. In other words, not all H.264 implementations are identical. Whilst on the encode side they'll all give you H.264 compliant-streams, and on the de-code side will all decode H.264 compliant streams, they won't all give you the same picture quality.
Next up is interlacing: interlacing is the process of dividing the picture up into odd and even lines. If the camera is an interlacing camera, even lines are captured, then odd lines are captured. The discussion of why you might want to do this is not important. Years ago, cameras were interlacing and TV sets were interlacing. Capture and playback methods matched up to one another.
Most modern forms of capturing and playing-back content don't use interlacing.
If you've got some interlaced content and need to display it on an LCD, plasma or DLP projector, you need to de-interlace it first. Simple you say: just take the one set of even lines, and the immediate next set of odd lines, and display them at the same time. Yes, you can do that, but it'll look rubbish. Why? Because the even and odd lines weren't captured at the same time, so if the subject and camera where moving relative to one another, there will be motion-related problems. Now, you can use loads of wicked-clever maths to overcome this problem (motion-compensated de-interlacing) and deliver a pretty damn good picture.
Next up, scaling: Imagine you've got a 640 x 360 pixel iTunes movie file, and your TV has 1360 x 768 pixels (a very common resolution for LCD tvs). How do you get your video to fill the screen completely, without having to crop it? On the horizontal scale, you've got 2.125 pixels on screen for each 1 pixel in the file, and on the vertical scale, you've got 2.133 pixels on screen for each 1 pixel in the file. Let's consider a single pixel in the very top left of the source file. Let's say it's coloured red. Which pixels on the screen should be coloured red? What's .125 of a pixel? .133 of a pixel? Again - here is where some clever maths is required to achieve optimal picture quality.
Now, let's review the process of playing back a file that contains an H.264 compressed video track - a stream of bits in an H.264-complaint structure that represents moving pictures:
- Decode H.264
- De-interlace (if the source is interlaced)
- Scale (if source resolution and display resolution don't match)
- Send data to screen
The AppleTV can do all these things. Each stage can contribute to the final picture quality achieved. The GeForce 7300 go can do all of these things in hardware, and it does it very well.With the Mac Mini, the GMA950 can do the de-interlacing and scaling in hardware, but it does it very poorly. You can do de-interlacing and scaling in software running on the Core2Duo processors, but the QuickTime de-interlacing and scaling isn't that good.
So, both AppleTV and Mac Mini have the potential to deliver top-notch picture quality, but it's much easier to achieve with the AppleTV since the hardware has all the functionality built-in already, it just needs relatively simple software (relative to the complex software-implementation of high-quality motion-compensated de-interlacing and scaling) to support those features.
For MPEG-4 content played on the AppleTV, the Geforce Go features are used, delivering superior picture quality relative to a Mac Mini. Using QuickTime plugins on the AppleTV however, all decoding, de-interlacing and scaling is performed on the CPU so will deliver equal performance to a Mac Mini. However, there is the potential there for Apple to deliver MPEG-2 and other codec support using some or all (depending on the codec in question) of the GeForce Go advanced features.
It is worth noting that most content won't be interlaced so the interlace performance might not matter all that much. I'm sure iTunes store files aren't interlaced, for example. It is also worth noting that interlaced content can be de-interlaced before being encoded. For example, a cable TV transmission may be interlaced. If you record this with a cable box, assuming the cable box doesn't do anything clever, you'll have an interlaced file. If you want to convert this file to H.264, you can as part of the process de-interlace the file before it's compressed. The quality of the algorithm used to de-interlace will affect the final picture quality of the file when it's played back; any de-interlacer in the playback hardware won't be needed and will therefore have no bearing on the final picture quality (but the H.264 decoder and scaling (if required) implementation will).
Having said all that Tenobell, here is the sequence of events in this thread from my point of view, with further expansion of each of the points I made:
Kip Kap Sol said people hacking the AppleTV might as well use a Mac Mini instead (i.e. - connect a Mac Mini to their TV, not an AppleTV to their TV)
I suggested that the AppleTV has superior video quality output than the Mac Mini. Whilst the Mac Mini has many advantages over an AppleTV in terms of range of capabilities, the AppleTV has superior video-playback hardware and therefore the potential for higher video output quality compared to a Mac Mini.
Then you said something along the lines of decent streaming performance and decent video output quality being mutually exclusive. I replied with a post pointing out that this is nonsense. Whether something is being streamed or read from HDD has no bearing on the quality of codec decoder, de-interlacer and scaler being used.
As long as the average bit-rate of the video being streamed is below the average throughput of the network over which it is being streamed, and the receiving device has a big enough buffer, there is no problem. Since the AppleTV will only go up to 720p and has 802.11n, and a 40 GB HDD (i.e. easily enough room for a, say, 20 second buffer), video bit-rate is not a problem in the context of streaming.
Then you made a post suggesting that if a Mac Mini is streaming to an AppleTV, the limiting factor will be the Mac Mini. In addition, you suggested that since the Mac Mini has a powerful Core2Duo processor, it doesn't matter that it has a GMA950 with rubbish video features.
I replied that your first point makes no sense (video output quality of a Mac Mini doesn't affect the video output quality of an AppleTV - the Mac Mini is sending a compressed video stream to the AppleTV, the Mac Mini is not modifying this stream in any way - it is the AppleTV that decodes the stream and displays the video) and that the second point could make sense but unfortunately Apple don't do all the things they'd need to do in software that the GMA doesn't do in hardware (and the Geforce 7300 does do in harware) to deliver maximum-quality pictures.
Wait... do you want us to share knowledge, or not? I'm confused.
You sound pretty smart, so I am surprised you are confused. Getting to the point, the answer is, yes, if you can manage to lose the snarkiness. O/w, I'll humbly repeat, shut up.
If we don't, it's no good, but if we do, we're out of touch with what users want. Eh?
And, if you don't, it's not necessarily "no good." We heathens will survive. (Btw, Canadian, eh?)
Translation: the computer that has your files can be a low-powered one, and the AppleTV will work. The speed of the network is the most important part. The Mac mini will be fine as a host for the AppleTV. Better?
No. (But thanks for the attempt at translation, despite it seeming to contradict other responses to the Mac Mini question).
Now, get back to your soldering.
You sound pretty smart, so I am surprised you are confused. Getting to the point, the answer is, yes, if you can manage to lose the snarkiness. O/w, I'll humbly repeat, shut up.
And, if you don't, it's not necessarily "no good." We heathens will survive. (Btw, Canadian, eh?)
No. (But thanks for the attempt at translation, despite it seeming to contradict other responses to the Mac Mini question).
Now, get back to your soldering.
anantksundaram, it is you that is being rude here, not me or Kickaha.
FYI, Kickaha is a programmer, not a hardware engineer. As far as I can tell, he really knows what he's doing. Most programmers of that capability that I know don't really like dealing with hardware so I imagine he doesn't play with a soldering iron all that much
The point remains that it seems odd to dispute a comment that someone makes if you don't really understand what's going on. You will note that Tenobell exchanged a few posts with me before he said he didn't understand what I was saying. Would it not have been a better idea for him to have said straight from the off he didn't get what I was saying, and to seek clarification? Instead he argued with me and proved in the process he doesn't understand the basics of video encoding, decoding and playback.
there are so many variable involed in video playback - you explained the process very very well
thanks
Oh crap. Look at this massive can of worms I opened! ...... to deliver maximum-quality pictures. (With a million or so words in-between I snipped)
Wow. Thanks. That was quite **phenomenal** by way of an explanation.
Yet, it does intrigue me that your say "So, both AppleTV and Mac Mini have the potential to deliver top-notch picture quality, but it's much easier to achieve with the AppleTV ....", a somewhat more hedged statement than the one prior. (In fairness, you do go on to explain the statement).
Truly, thanks again.
anantksundaram, it is you that is being rude here, not me or Kickaha.
FYI, Kickaha is a programmer, not a hardware engineer. As far as I can tell, he really knows what he's doing. Most programmers of that capability that I know don't really like dealing with hardware so I imagine he doesn't play with a soldering iron all that much
The point remains that it seems odd to dispute a comment that someone makes if you don't really understand what's going on. You will note that Tenobell exchanged a few posts with me before he said he did understand what I was saying. Would it not have been a better idea for him to have said straight from the off he didn't get what I was saying, and to seek clarification? Instead he argued with me and proved in the process he doesn't understand the basics of video encoding, decoding and playback.
Look, I honestly did not mean to be rude. (See above, which I replied to before your response to my response to Kickaha). I apologize for sounding ticked off.
My point is simple, and by now, should perhaps be obvious: Forums like these have as members that float in and out, that are young and old (posts-wise), are novices and pros (on a given issue). The fact that someone is "in," "old" and "pro" (or any other combination) has zero bearing.
No one is required to respond to anything.
There are a million forums like this, but I signed on to (and bother to stay involved with) AI only because I saw that AI seemed a little different, and actually, a bit more mature than the rest.
I have no problem at all being called on something. I expect that most people who post here -- regardless of vintage, knowledge, etc -- would feel the same way. (If that's not the case, I realize that one can simply pack up and leave).
Look, I honestly did not mean to be rude. (See above, which I replied to before your response to my response to Kickaha). I apologize for sounding ticked off.
My point is simple, and by now, should perhaps be obvious: Forums like these have as members that float in and out, that are young and old (posts-wise), are novices and pros (on a given issue). The fact that someone is "in," "old" and "pro" (or any other combination) has zero bearing.
No one is required to respond to anything.
There are a million forums like this, but I signed on to (and bother to stay involved with) AI only because I saw that AI seemed a little different, and actually, a bit more mature than the rest.
I have no problem at all being called on something. I expect that most people who post here -- regardless of vintage, knowledge, etc -- would feel the same way. (If that's not the case, I realize that one can simply pack up and leave).
Thank you for your post. I in turn apologise for rubbing you up the wrong way. It's 04:35 AM here so I really should have gone to bed hours ago! I would agree with you that on the whole, AI forums tend to be more balanced and mature with fewer flame-fests than other boards.
Glad you liked my mammoth post