[issue1850] AC3 transcode (eg to WAV) - bad audio
Justin Ruggles justin.rugg...@gmail.com added the comment: So right now the application can know that the number of channels changes because avctx-channels changes. But I guess it wouldn't hurt to log a warning in the decoder when the number of channels changes and the decoder goes from matching request_channels to not matching it. Or just log it either way. Same probably goes for sample rate too. FFmpeg issue tracker iss...@roundup.ffmpeg.org https://roundup.ffmpeg.org/issue1850
[issue1850] AC3 transcode (eg to WAV) - bad audio
New submission from Antr ant20...@gmail.com: ffmpeg.exe -i test.ac3 -acodec pcm_s16le -f wav -ac 6 test.wav Tested in VLC File 'test.ac3' not attached - you can download it from https://roundup.ffmpeg.org/file854. -- files: test.ac3 messages: 10003 priority: normal status: new substatus: new title: AC3 transcode (eg to WAV) - bad audio type: bug FFmpeg issue tracker iss...@roundup.ffmpeg.org https://roundup.ffmpeg.org/issue1850
[issue1850] AC3 transcode (eg to WAV) - bad audio
Justin Ruggles justin.rugg...@gmail.com added the comment: So what happens is that when the stream changes to stereo, the decoder will start outputting stereo. The audio seems correct though. But since the output format is wav, it expects everything to be the same channel layout. So when it changes to stereo, it throws off the channel order. So after that point the channels are interpreted as Rs, LFE, L, C, R, Ls instead of L, C, R, Ls, Rs, LFE. The next question is, should FFmpeg do anything about this? When the mid-stream switch is the other way (stereo-5.1-stereo) we handle it by downmixing the 5.1 content to match. But in this case we don't upmix the stereo content to match the 5.1 content. We just change AVCodecContext.channels to 2 and start outputting stereo. FFmpeg issue tracker iss...@roundup.ffmpeg.org https://roundup.ffmpeg.org/issue1850
