When streaming Apple Lossless files on on Apple TV, what is the maximum bitrate? I realize Apple TV can stream AAC and MP3 files at 320 kbps, but what about Apple Lossless file that can often provide up to 1,000 kbps? Does Apple TV support such high bitrates? (I know the sampling is always 16 bit / 48 kHz).
Apple TV (2nd generation)
yup. your lossless files will go over your wifi as uncompressed 16bit/48k streams.
16 bit ("world length") x 48000 words per second x 2 (left and right channels) = 1,536,000 bps = 1536 kpbs.
yup. your lossless files will go over your wifi as uncompressed 16bit/48k streams.
16 bit ("world length") x 48000 words per second x 2 (left and right channels) = 1,536,000 bps = 1536 kpbs.
Hi. Thanks for the reply. Greatly appreciated.
But I have more questions.
Your equation seems to assume that all 16 bit signals produce bitrates at 1500kbs. However, the AAC files are limited to 320kbs. I am probably wrong about this.
As well, I can't explain why it is that Alac lossless files played through Apple TV sound no better than AAC files played at 256 Kbps.
Hello. For some reason, your reply to my May 2 post, has disappeared, though I still have it in email. I've reposted in below.
First, let me thank you for taking the time to answer my questions. I'm confident that you've zeroed in on a solution. The clarity of your response is greatly appreciated.
Your points about compressed/lossy formats make sense. This explains the lower bitrates for those formats.
You also asked about the original source of my alac (Apple Lossless) files. As you may have guessed, the original files are typical itunes downloads, which I understand are usually MP3s at 256 kbps.
I had assumed that running them through the itunes converter would transform them into proper (16/44.1) lossless files with the associated bitrates ranging around 1,000 kbps -- with a much richer sound.
At first glance, it would appear that I was wrong. Merely upsampling the music has created larger files but without the added clarity, depth and soundstage. That's how I read your previous post. Again, correct me if I am wrong about this.
However, there is a twist.
As I mentioned, when I play these alac files through Apple TV -- through homesharing on my computer -- they sound no better than the 256k files. However, when I play the same files through the foobar2000 media streaming software, they sound much better and show the proper bitrates at around 1,000 kbps.
On this last question, my ears may be playing tricks on me, but I don't think so. I'm playing the files through a good system: an audiolab 8200CDQ pre-amp and 8200p power amp.
So, this has me stumped.
One last question: what is the point of having a program that upconverts MP3/AAC files to lossless if there is no improvement in sound quality. Why would you have a bigger file that sounds just as bad as the small one?
Regards
Here is your May 3 post, which has disappeared from the websit.
May 3
No problem. Sorry for the long reply.
I see what you mean about my equation. All 16/48 stereo signals would equate to 1536kbps. If you changed the sample rate to 44.1 (what CDs use) or something else, then the bitrate would change.
Now thats for uncompressed formats like WAV, AIFF, and PCM. And in the case of Airplay, the stream getting sent to the AppleTV is always uncompressed, no matter the the original format (aac, mp3, apple lossless, etc).
AAC files (and mp3, wma) are known as compressed formats: some fancy math equations are used to reduce the file size w/o your brain noticing the missing bits, so that initial stream (1536 kbps for instance) gets reduced to 320 kbps or lower in order to fit more songs on your device. the way this happens is really crazy but if you want to learn about it theres a magazine that did a good article. WARNING, its really technical!: http://www.soundonsound.com/sos/apr12/articles/lost-in-translation.htm
you seem to be able to hear the difference between compressed and uncompressed formats. many people do but many dont. It all depends on your hearing, sound equipment, etc. I was wondering if the reason your not hearing a difference btwn apple lossless and aac might be because of where the lossleess files came from. did you rip them from CD's or convert them from another format? If they didn't come from CD's, WAV, or AIFF files, you probably won't hear a difference, because you can't "upconvert" from something like AAC to Apple Lossless and get higher sound quality. If they came from CDs, then maybe the AAC versions are just really good quality to begin with and so you are having a hard time telling. That article has some examples of the same music in different formats, so you can test your ears and see if you notice a difference.
bE
Hello MicMac64,
A rough conversion from a given bitrate to a higher one won't change sound quality. But if you use a high quality upscaler you might be able to guess better what the original sound was like.
I'll try to explain it without being too technical.
First you convert sound (analogic) to a numeric file. It's like drawing a curve on a grid then choosing on square per colomn to represent the curve. Those squares are the music in digital form. The higher density is the grid, the more precision you get.
When playing, your DAC (digital to analog converter) does the opposite. It uses the squares and tries to guess the curve the best it can.
Upscalling is the process of densifying the grid, trying to match what was the curve in the first place. It requires tons of complicated math to be effective but can help a lot.
Hope this helps !
There is nothing to be gained going from a lossy file (or a more compact file with lower bitrate) and "up" converting it to a Lossless file type.
Any audio information the original encoding in AAC format that was deemed redundant and discarded for the sake of making that file more compact and easily downloaded will not be restored when transcoding the already degraded file into Apple Lossless, the damage (whether you can hear it or not) has already been done.
For files purchased through the iTunes store, you are better off listening to them in their original resolution rather than transcoding them to a superior file type. For files that are already Lossless or uncompressed like .wav or .flac files that you wish to import into your iTunes library, there should be no loss of fidelity when importing into Apple Lossless or transcoding from one lossless file type to one compatible with iTunes.
Apple Lossless streaming on Apple TV
