[Ffmpeg-devel] mpeg2 program stream with LPCM question.
Mon Jun 13 21:47:27 CEST 2005
M?ns Rullg?rd wrote:
>>I have a couple of question about LPCM in mpeg program stream files. This
>>is for my own program stream reader in mpeg4ip, although ffplay doesn't
>>seem to play this particular file (made with Adobe's mpeg encoder).
> We'd appreciate a sample of anything that doesn't decode correctly.
> Could you please upload a few megabytes?
Uploaded to wmay_mpeg2 directory, test.mpg.
Crash report follows below:
> The LPCM header is 7 bytes in all, including the substream id. I
> found this description somewhere:
> id 8 bit
> number of frames 8 bit
> first acces unit pointer, i.e. start of audio frame 16 bit
> audio emphasis on-off 1 bit
> audio mute on-off 1 bit
> reserved 1 bit
> audio frame number 5 bit
> quantization word length 2 bit
> audio sampling frequency (48khz = 0, 96khz = 1) 2 bit
> reserved 1 bit
> number of audio channels - 1 (e.g. stereo = 1) 3 bit
> dynamic range control (0x80 if off) 8 bit
> The PTS refers to the first start of a frame in the PES packet. One
> frame is 150 PTS ticks in length, or 80 samples at 48kHz. The first
> PES packet will contain a little over 6 frames, and the second packet
> will begin with the remainder of the 7th frame. The PTS of the second
> packet refers to the start of the 8th frame, the location of which is
> specified in the LPCM header.
Thanks. That's what I needed, exactly. It's working now, in my code.
The crash report (on the latest ffmpeg CVS version) follows.
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