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Topic: Clipping When Decoding DTS with FFMPEG (Read 7393 times) previous topic - next topic
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Clipping When Decoding DTS with FFMPEG

The DTS stream comes from Transporter 3 on Blu-ray.  I have extracted the core DTS stream using tsmuxer.  I then decoded this stream and reordered the channels:

Code: [Select]
ffmpeg -i audio_51.dts -f s16le audio_51.raw
sox -t raw -s -2 -c 6 -r 48000 audio_51.raw -t raw -s -2 -c 6 -r 48000 audio_51_temp.raw remix 1 3 2 5 6 4
mv audio_51_temp.raw audio_51.raw

AFAIK, this problem is occuring at the first line, as the second two reorder the channels and rename the raw PCM file.

I have also posted a screenshot of the clipping.

What can be done to avoid this?  Is there a way to decode the DTS stream without increasing the volume?

Clipping When Decoding DTS with FFMPEG

Reply #2 –
Huh, I think I figured it out.  The clipping is occurring on the rear channels.  Now AFAIK, Transporter 3's DTS-HD MA stream is 7.1, but since FFMPEG doesn't understand this, it gets downmixed to 5.1 and the back channels get combined from four into two.

Clipping When Decoding DTS with FFMPEG

Reply #3 –
If you're working with HD audio tracks, I'd suggest transcoding with eac3to in all cases. It uses a modified version of libavcodec (and can hook into Nero / Sonic / Arcsoft DLLs) to always provide clipping-free output.

It's amazingly good. Seriously, check it out  It's been tested on so many different HD-DVD and BluRay sources that it's ferreted out almost every imaginable bug or wierdness

~MiSfit

Clipping When Decoding DTS with FFMPEG

Reply #4 –
Quote from: wswartzendruber on
Huh, I think I figured it out.  The clipping is occurring on the rear channels.  Now AFAIK, Transporter 3's DTS-HD MA stream is 7.1, but since FFMPEG doesn't understand this, it gets downmixed to 5.1 and the back channels get combined from four into two.

Hi, above you wrote that you extracted the DTS-core stream via TSMuxer, which is then a 5.1-version. Hence the rationale
for the clipping being the result of downmixing in the surround channels seems to be wrong...
Cheers

Clipping When Decoding DTS with FFMPEG

Reply #5 –
Quote from: blue_misfit on
If you're working with HD audio tracks, I'd suggest transcoding with eac3to in all cases. It uses a modified version of libavcodec (and can hook into Nero / Sonic / Arcsoft DLLs) to always provide clipping-free output.


How is it modified? We really prefer these things be submitted upstream...