Quote:
Originally Posted by hello_hello
Lossy audio doesn't have a fixed bitdepth.
Bitrate = the number of samples per second. For lossless audio bitdepth = the range of values that can be assigned to any one of those samples. For 8 bit it's 256, for 16 bit it's 65,536 and for 24 bit it's 16,777,216.
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Oh, I thought (for lossless audio) kHz defines how much samples per second are taken and Bit depth how many values each sample stores. And I thought AC-3 would work like eg. x264 which keeps the bitrate low when there is no content to encode. So in short AC-3 is like MP3 CBR?!
Quote:
Originally Posted by hello_hello
I'd assume because the DTS-HD audio is lossless the bitdepth is known. For your example it was originally 16 bit, it was encoded at 16 bit, and eac3to decoded it as 16 bit and fed that to the AC3 encoder. DTS-HD supports 24 bit lossless, but it appears you have 16 bit DTS-HD.
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I have other files. Some with 24-Bit DTS-HD and 16-Bit DTS Core, some with 16-Bit DTS-HD and 24-Bit Core and last but not least 16-Bit/16-Bit as well as 24-Bit/24-Bit. I just re-checked with MediaInfo and even for (lossy) DTS I get a Bitdepth shown.
Quote:
Originally Posted by hello_hello
It's kind of like converting a 16 bit wave file to a 16 bit flac file and then back to a 16 bit wave file again. Nothing is lost, and in your first example you've effectively converted that second wave file to AC3.
Lossy audio can be decoded to any fixed bitdepth. The greater the bitdepth, the more accurately it can be decoded. eac3to decodes the lossy DTS core, which has no fixed bitdepth, to a fixed bitdepth of 24 bits.
It's kind of like converting a 16 bit wave file to an MP3 and then decoding the MP3 to a 24 bit wave file. What was lost during the MP3 conversion is gone forever despite the output bitdepth being greater.
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Yeah, that is the part I already knew. I ripped my Audio-CDs with the Fraunhofer MP3 codec when it was leaked back then and still do some re-encodings today from CD to FLAC. Also read (and understood = the important part
)
https://www.highresaudio.com/texte.php?ca_id=92
One last question: In
http://forum.doom9.org/showthread.php?t=27131 I read that based on the bitrate AC-3 limits the available frequency range, eg. 256 kbps up to 12 kHz, 384 kbps up to 18 kHz and 448 kbps or higher with full 20 kHz. Is that true? I thought that a 2 channel 224 kbps AC-3 has a better quality per channel than a 6 channel 640 kbps AC-3. Maybe I should just go with 640 regardless of the amount of channels?
