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April 2024

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#10878(undetermined:new): Muxing PCM_S24LE Audio Into MP4 Incorrectly Marked as 16-Bit
by FFmpeg 02 Apr '24

02 Apr '24

#10878: Muxing PCM_S24LE Audio Into MP4 Incorrectly Marked as 16-Bit -------------------------------------+------------------------------------- Reporter: | Type: defect HyperStryker | Status: new | Priority: important Component: | Version: git- undetermined | master Keywords: pcm_s24le | Blocked By: mp4 wav mov muxing ipcm | Blocking: | Reproduced by developer: 0 Analyzed by developer: 0 | -------------------------------------+------------------------------------- Summary of the bug: When muxing an H264-encoded video in a .MOV container with a .WAV file containing PCM_S24LE audio to an .MP4 container (discarding original video audio), the resulting file purportedly contains PCM_S24LE audio, but is incorrectly marked as 16-bit when checking the resulting .MP4 file in Mediainfo: {{{ Audio ID : 2 Format : PCM Format settings : Little / Signed Codec ID : ipcm Duration : 56 min 5 s Bit rate mode : Constant Bit rate : 1 536 kb/s Maximum bit rate : 2 304 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Bit depth : 16 bits Stream size : 924 MiB (8%) Default : Yes Alternate group : 1 }}} FFmpeg in the command line shows the resulting audio still in the PCM_S24LE format when muxing (using an PCM_S24LE audio-only .MOV file instead of .WAV, made no practical difference): {{{ Stream #0:1(eng): Audio: pcm_s24le (ipcm / 0x6D637069), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default) Metadata: creation_time : 2024-02-21T04:54:45.000000Z handler_name : Apple Sound Media Handler vendor_id : timecode : 00:00:00:00 }}} Further, when extracting/stream-copying the audio from the .MP4 file back into a .WAV file, FFmpeg notes: {{{ [wav @ 000002532f935a80] requested bits_per_coded_sample (16) and actually stored (24) differ }}} This lined up with me checking the same .MP4 file in Adobe Audition, which reported the file as containing 24-bit audio instead of 16-bit. How to reproduce: Muxing .MOV and .WAV to .MP4 {{{ ffmpeg -i in1.mov -i in2.wav -map 0:v -map 1:a -c copy out.mp4 }}} Stream copying back to .WAV {{{ ffmpeg -i out.mp4 -map 0:a -c copy out2.wav }}} -- Ticket URL: <https://trac.ffmpeg.org/ticket/10878> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker

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Re: [FFmpeg-trac] #98(undetermined:closed): Channel reordering in pcm files
by FFmpeg 02 Apr '24

02 Apr '24

#98: Channel reordering in pcm files -------------------------------------+------------------------------------- Reporter: Carl Eugen | Owner: (none) Hoyos | Type: defect | Status: closed Priority: minor | Component: | undetermined Version: git-master | Resolution: fixed Keywords: chan | Blocked By: Blocking: | Reproduced by developer: 1 Analyzed by developer: 1 | -------------------------------------+------------------------------------- Changes (by Marton Balint): * status: open => closed * resolution: => fixed Comment: Fixed in e6c2c8703732bc46395c65c530038c8146df0deb. -- Ticket URL: <https://trac.ffmpeg.org/ticket/98#comment:6> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker

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