[FFmpeg-user] Different MD5 hashes for identical tracks

[Moritz Barsnick]

On Tue, Jun 30, 2020 at 19:31:24 +0300, raistlin.mlists at yandex.ru wrote:
> There are 2 sample m2ts files (about 84 MB each):
> https://mir.cr/0Y8ROTYT (1)
> https://mir.cr/RFI1MNOM (2)
>
> Stream a:5 in (1) and stream a:4 in (2) are identical (being binary
> compared). Though ffmpeg reports they have different MD5 hashes:
>
> ffmpeg -loglevel 4 -i 00001.m2ts -map 0:a:5 -codec copy -f md5 -
> MD5=cee9775826b81d395c7d012e69309270

    Stream #0:0[0x1011]: Video: h264 (High) (HDMV / 0x564D4448), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
    Stream #0:1[0x1100](rus): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 384 kb/s
    Stream #0:2[0x1101](rus): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 448 kb/s
    Stream #0:3[0x1102](rus): Audio: dts (DTS) ([130][0][0][0] / 0x0082), 48000 Hz, 5.1(side), fltp, 1536 kb/s
    Stream #0:4[0x1103](eng): Audio: truehd (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), s32 (24 bit)
    Stream #0:5[0x1103]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 640 kb/s
    Stream #0:6[0x1104](eng): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, stereo, fltp, 192 kb/s

> ffmpeg -loglevel 4 -i 00000.m2ts  -map 0:a:4 -codec copy -f md5 -
> MD5=32ccb6d7af46bfdd2100cd68c7622171

    Stream #0:0[0x1011]: Video: h264 (High) (HDMV / 0x564D4448), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
    Stream #0:1[0x1100](eng): Audio: truehd (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), s32 (24 bit)
    Stream #0:2[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 640 kb/s
    Stream #0:3[0x1101](rus): Audio: dts (DTS) ([130][0][0][0] / 0x0082), 48000 Hz, 5.1(side), fltp, 1536 kb/s
    Stream #0:4[0x1102](rus): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 640 kb/s
    Stream #0:5[0x1103](ukr): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, stereo, fltp, 448 kb/s

192 kb/s stereo vs. 448 kb/s stereo.
They can't be identical, can they?

Moritz