Difference between 2 dts files.

[infini]

I have extracted 2 .dts files from 2 different .mkv files (same movie). The one is reported from mediainfo as 1509kbps, 16bits, 6channels, DTS (MA/Core) with size 1.71GB, and the other is 1509kbps, 24bits, 6channels, DTS with size 1.20GB. How is it possible that the 24bit .dts file is smaller size? I think it is supposed to give better quality and so it should be larger.

[Baldrick]

Bitrate*running time= file size. It doesn't matter if it's 24bits or 16bits or anything else.

But if both have same bitrate they should be same size. Mediainfo might just show wrong information.

[infini]

Running time is the same because it is the same movie.

[El Heggunte]

How is it possible that the 24bit .dts file is smaller size? I think it is supposed to give better quality and so it should be larger.

The first file in your example is DTS-HD Master Audio, whereas the second one is "plain" DTS (*dca*, if we want to go technical). For lossy DTS, 16-bits or 24-bits is just a flag in the frame headers of the stream, and it's just a signal for the decoders, some decoders always decode to 24-bit anyway, whereas other decoders won't decode to 24-bits unless the frame headers of the stream indicate 24-bits (this is madshi's reasoning, bien entendu):

(1) Each DTS frame contains a header field which informs us about whether the original source was 16bit or 24bit. In theory this header field is only for our information and should not be used during decoding (except for DTS-HD MA where due to being lossless the final output should have the same bitdepth as the original source). Because this header field is only for our information, and should not really be used during decoding, it should not *harm* to modify it (again: the exception is DTS-HD MA).

(2) There are some decoders which always limit their output to the bitdepth of the original audio source - even for lossy DTS. That means, if the header field says that the original audio data was only 16bit, then the decoder only outputs 16bit, too. This is *BAD* because lossy formats decode always to higher than 16bit (doesn't matter which bitdepth the original source had), and if the decoder downconverts that to 16bit, we lose quality.

Now combine the two facts above and you will see that what eac3to does, shouldn't ever harm, but it will sometimes (with stupid decoders) help to get higher quality playback.

( source: http://forum.doom9.org/showthread.php?p=1386479#post1386479 )

[infini]

So, which of the 2 files you think has better audio quality? Annd generally, 24bit is better that 16bit?

[El Heggunte]

The lossless one (Master Audio) must have better quality, because it's faithful to the original, uncompressed source

Lossy DTS never can give you a bit-exact copy of the uncompressed source, regardless of the bit-depth flag (16-bits, 24-bits, whatever).