Opened 3 months ago

Last modified 7 weeks ago

#7282 new defect

ffmpeg generates improper HE-AACv2 fMP4 files

Reported by: ronak2121 Owned by:
Priority: normal Component: undetermined
Version: git-master Keywords:
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Summary of the bug:

ffmpeg is unable to generate HE-AACv2 fMP4 files that can be properly read by non-ffmpeg tooling as HE-AACv2. This is because the defaultSampleDuration inside of the moof atoms is set to 2048, instead of 1024, just like it is for LC-AAC.

It seems like ffmpeg does not properly read the HE-AACv2 profile when writing into the defaultSampleDuration field in the moof atom.

How to reproduce:

% ffmpeg -i "$FILE.mp4" -codec copy -hls_time 0.975238095238095 -hls_segment_type fmp4 -hls_flags single_file+append_list+split_by_time -hls_playlist_type vod "$FILE.m3u8"

with an HE-AACv2 audio file created by the same version of ffmpeg.

ffmpeg version

ffmpeg version git-2018-06-23-b86c575 Copyright (c) 2000-2018 the FFmpeg
developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-b86c575 --enable-
shared --enable-pthreads --enable-version3 --enable-hardcoded-tables
--enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl
--enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-
librubberband --enable-libvorbis --enable-libvpx --enable-libx264
--enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
--enable-nonfree
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 20.103 / 58. 20.103
  libavformat    58. 17.101 / 58. 17.101
  libavdevice    58.  4.101 / 58.  4.101
  libavfilter     7. 25.100 /  7. 25.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100

Change History (14)

comment:1 Changed 3 months ago by ronak2121

Just to clarify, the audio files are created at 44.1kHz & 32 kbps using the HE-AACv2 profile from lib_fdkaac.

comment:2 Changed 3 months ago by cehoyos

  • Component changed from avformat to undetermined
  • Priority changed from important to normal

What makes you believe the files are improper?
Is the issue only reproducible with -acodec copy or also if you encode with ffmpeg?

Please provide the command line you tested together with the complete, uncut console output to make this a valid ticket.

comment:3 Changed 3 months ago by ronak2121

Here's what I did:

First, I created an HE-AACv2 MP4 from a Wav file:

ffmpeg -i short_44khz_16bit_2ch.wav -r:a 44100 -b:a 32k -codec libfdk_aac -profile:a aac_he_v2 test.aac

with this console output:

a45e60e46a79:input ronakp$ ffmpeg -i short_44khz_16bit_2ch.wav -r:a 44100 -b:a 32k -codec libfdk_aac -profile:a aac_he_v2 test.aac
ffmpeg version git-2018-06-23-b86c575 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-b86c575 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-nonfree
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 20.103 / 58. 20.103
  libavformat    58. 17.101 / 58. 17.101
  libavdevice    58.  4.101 / 58.  4.101
  libavfilter     7. 25.100 /  7. 25.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'short_44khz_16bit_2ch.wav':
  Duration: 00:09:44.61, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
File 'test.aac' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
Output #0, adts, to 'test.aac':
  Metadata:
    encoder         : Lavf58.17.101
    Stream #0:0: Audio: aac (libfdk_aac) (HE-AACv2), 44100 Hz, stereo, s16, 32 kb/s
    Metadata:
      encoder         : Lavc58.20.103 libfdk_aac
size=    2284kB time=00:09:44.65 bitrate=  32.0kbits/s speed=67.1x    
video:0kB audio:2284kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

Once I fragment this file with this command:

ffmpeg -i "test.aac" -codec copy -bsf:a aac_adtstoasc -hls_time 9.75238095238095 -hls_segment_type fmp4 -hls_flags single_file+append_list+split_by_time -hls_playlist_type vod "test.m3u8"
ffmpeg version git-2018-06-23-b86c575 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-b86c575 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-nonfree
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 20.103 / 58. 20.103
  libavformat    58. 17.101 / 58. 17.101
  libavdevice    58.  4.101 / 58.  4.101
  libavfilter     7. 25.100 /  7. 25.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
[aac @ 0x7ff9cd001200] Estimating duration from bitrate, this may be inaccurate
Input #0, aac, from 'test.aac':
  Duration: 00:10:13.76, bitrate: 30 kb/s
    Stream #0:0: Audio: aac (HE-AACv2), 44100 Hz, stereo, fltp, 30 kb/s
[hls @ 0x7ff9cd001e00] Opening 'test.m4s' for writing
Output #0, hls, to 'test.m3u8':
  Metadata:
    encoder         : Lavf58.17.101
    Stream #0:0: Audio: aac (HE-AACv2), 44100 Hz, stereo, fltp, 30 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[hls @ 0x7ff9cd001e00] Opening 'test.m3u8.tmp' for writing
    Last message repeated 58 times
[hls @ 0x7ff9cd001e00] Opening 'test.m3u8.tmp' for writing
size=N/A time=00:09:44.77 bitrate=N/A speed=6.29e+03x    
video:0kB audio:2198kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Open the M4S file, and look at the moof -> traf -> tfhd atom. The defaultSampleDuration is set to 2048.

If you use Apple's mediafilesegmenter tool, the defaultSampleDuration is set to 1024 instead.

mediafilesegmenter -a -s -r -B test_apple -i test_apple.m3u8 -t 10 test.aac

a45e60e46a79:input ronakp$ mediafilesegmenter -a -s -r -B test_apple -i test_apple.m3u8 -t 10 test.aac
Jun 27 2018 09:38:41.908: ISO fragmented mode, forcing segments to start with I-Frame
Jun 27 2018 09:38:41.908: Processing file /Users/ronakp/Downloads/input/test.aac
Jun 27 2018 09:38:41.934: Wrote 0 to 621 to test_apple.mp4
Jun 27 2018 09:38:41.937: Wrote 621 to 40406 to test_apple.mp4
Jun 27 2018 09:38:41.937: segment bitrate 31.88 kbits/sec is new max
Jun 27 2018 09:38:41.941: Wrote 40406 to 79905 to test_apple.mp4
Jun 27 2018 09:38:41.945: Wrote 79905 to 119449 to test_apple.mp4
Jun 27 2018 09:38:41.948: Wrote 119449 to 158987 to test_apple.mp4
Jun 27 2018 09:38:41.952: Wrote 158987 to 198420 to test_apple.mp4
Jun 27 2018 09:38:41.955: Wrote 198420 to 238025 to test_apple.mp4
Jun 27 2018 09:38:41.959: Wrote 238025 to 277563 to test_apple.mp4
Jun 27 2018 09:38:41.963: Wrote 277563 to 317093 to test_apple.mp4
Jun 27 2018 09:38:41.966: Wrote 317093 to 356553 to test_apple.mp4
Jun 27 2018 09:38:41.970: Wrote 356553 to 396035 to test_apple.mp4
Jun 27 2018 09:38:41.974: Wrote 396035 to 435570 to test_apple.mp4
Jun 27 2018 09:38:41.978: Wrote 435570 to 475084 to test_apple.mp4
Jun 27 2018 09:38:41.982: Wrote 475084 to 514572 to test_apple.mp4
Jun 27 2018 09:38:41.985: Wrote 514572 to 554179 to test_apple.mp4
Jun 27 2018 09:38:41.988: Wrote 554179 to 593620 to test_apple.mp4
Jun 27 2018 09:38:41.992: Wrote 593620 to 633215 to test_apple.mp4
Jun 27 2018 09:38:41.994: Wrote 633215 to 672645 to test_apple.mp4
Jun 27 2018 09:38:41.998: Wrote 672645 to 712211 to test_apple.mp4
Jun 27 2018 09:38:42.002: Wrote 712211 to 751692 to test_apple.mp4
Jun 27 2018 09:38:42.006: Wrote 751692 to 791271 to test_apple.mp4
Jun 27 2018 09:38:42.008: Wrote 791271 to 830777 to test_apple.mp4
Jun 27 2018 09:38:42.012: Wrote 830777 to 870272 to test_apple.mp4
Jun 27 2018 09:38:42.015: Wrote 870272 to 909738 to test_apple.mp4
Jun 27 2018 09:38:42.018: Wrote 909738 to 949296 to test_apple.mp4
Jun 27 2018 09:38:42.022: Wrote 949296 to 988788 to test_apple.mp4
Jun 27 2018 09:38:42.026: Wrote 988788 to 1028358 to test_apple.mp4
Jun 27 2018 09:38:42.030: Wrote 1028358 to 1067856 to test_apple.mp4
Jun 27 2018 09:38:42.034: Wrote 1067856 to 1107335 to test_apple.mp4
Jun 27 2018 09:38:42.037: Wrote 1107335 to 1146795 to test_apple.mp4
Jun 27 2018 09:38:42.041: Wrote 1146795 to 1186399 to test_apple.mp4
Jun 27 2018 09:38:42.044: Wrote 1186399 to 1225815 to test_apple.mp4
Jun 27 2018 09:38:42.047: Wrote 1225815 to 1265449 to test_apple.mp4
Jun 27 2018 09:38:42.051: Wrote 1265449 to 1304925 to test_apple.mp4
Jun 27 2018 09:38:42.054: Wrote 1304925 to 1344382 to test_apple.mp4
Jun 27 2018 09:38:42.058: Wrote 1344382 to 1383935 to test_apple.mp4
Jun 27 2018 09:38:42.062: Wrote 1383935 to 1423498 to test_apple.mp4
Jun 27 2018 09:38:42.066: Wrote 1423498 to 1462984 to test_apple.mp4
Jun 27 2018 09:38:42.069: Wrote 1462984 to 1502553 to test_apple.mp4
Jun 27 2018 09:38:42.073: Wrote 1502553 to 1542116 to test_apple.mp4
Jun 27 2018 09:38:42.076: Wrote 1542116 to 1581536 to test_apple.mp4
Jun 27 2018 09:38:42.081: Wrote 1581536 to 1621122 to test_apple.mp4
Jun 27 2018 09:38:42.084: Wrote 1621122 to 1660673 to test_apple.mp4
Jun 27 2018 09:38:42.089: Wrote 1660673 to 1700069 to test_apple.mp4
Jun 27 2018 09:38:42.093: Wrote 1700069 to 1739661 to test_apple.mp4
Jun 27 2018 09:38:42.096: Wrote 1739661 to 1779163 to test_apple.mp4
Jun 27 2018 09:38:42.100: Wrote 1779163 to 1818692 to test_apple.mp4
Jun 27 2018 09:38:42.103: Wrote 1818692 to 1858169 to test_apple.mp4
Jun 27 2018 09:38:42.106: Wrote 1858169 to 1897711 to test_apple.mp4
Jun 27 2018 09:38:42.109: Wrote 1897711 to 1937200 to test_apple.mp4
Jun 27 2018 09:38:42.113: Wrote 1937200 to 1976758 to test_apple.mp4
Jun 27 2018 09:38:42.117: Wrote 1976758 to 2016276 to test_apple.mp4
Jun 27 2018 09:38:42.120: Wrote 2016276 to 2055769 to test_apple.mp4
Jun 27 2018 09:38:42.122: Wrote 2055769 to 2095311 to test_apple.mp4
Jun 27 2018 09:38:42.124: Wrote 2095311 to 2134807 to test_apple.mp4
Jun 27 2018 09:38:42.127: Wrote 2134807 to 2174290 to test_apple.mp4
Jun 27 2018 09:38:42.129: Wrote 2174290 to 2213898 to test_apple.mp4
Jun 27 2018 09:38:42.134: Wrote 2213898 to 2253400 to test_apple.mp4
Jun 27 2018 09:38:42.138: Wrote 2253400 to 2292947 to test_apple.mp4
Jun 27 2018 09:38:42.140: Wrote 2292947 to 2303705 to test_apple.mp4
Jun 27 2018 09:38:42.140: Unknown video dynamic range value 0
Jun 27 2018 09:38:42.140: average bit rate is 31.68 kbits/sec - max file bit rate is 31.88 kbits/sec

Looking at this file, the defaultSampleDuration is set to 1024, which is correct at a 44100Hz sampling rate.

Another issue is if you compare the codec outputs using Apple's tooling for both files:

M3U8 created by FFMPEG
mediastreamvalidator test.m3u8

the output is:

Track ID: 1
Audio Codec: AAC-LC
Audio sample rate: 22050 Hz
Audio channels: 1
Audio channel layout: Mono

If you look at the file generated by Apple's tool:

M3U8 created by Apple
mediastreamvalidator test_apple.m3u8

the output is:

Track ID: 1
Audio Codec: AAC-HEv2
Audio sample rate: 44100 Hz
Audio channels: 2
Audio channel layout: Stereo (L R)

Running ffprobe -i on the Apple Generated fragmented MP4:

ffprobe -i test_apple.mp4 
ffprobe version git-2018-06-23-b86c575 Copyright (c) 2007-2018 the FFmpeg developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-b86c575 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-nonfree
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 20.103 / 58. 20.103
  libavformat    58. 17.101 / 58. 17.101
  libavdevice    58.  4.101 / 58.  4.101
  libavfilter     7. 25.100 /  7. 25.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test_apple.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 1
    compatible_brands: mp41mp42isomhlsf
    creation_time   : 2018-06-27T13:38:41.000000Z
  Duration: 00:09:50.50, start: 9.904218, bitrate: 31 kb/s
    Stream #0:0(und): Audio: aac (HE-AACv2) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 30 kb/s (default)
    Metadata:
      creation_time   : 2018-06-27T13:38:41.000000Z
      handler_name    : Core Media Audio

So, in conclusion, here are the problems:

  1. It looks like ffmpeg's MP4 or fMP4 generation process ends up stripping the HE-AACv2 profile in a way that Apple's tooling does not recognize the profile anymore. This leads to players not always recognizing the profile properly and playing at degraded quality.
  2. The different defaultSampleDuration ends up causing issues when doing Adaptive Streaming between HE-AAC and LC-AAC audio streams in players like Exoplayer. I've filed an issue against Exoplayer and is how we discovered this problem: https://github.com/google/ExoPlayer/issues/3971
Last edited 3 months ago by cehoyos (previous) (diff)

comment:4 Changed 3 months ago by cehoyos

Is the issue only reproducible if you remux the file or also if you (re-)encode?

comment:5 follow-up: Changed 3 months ago by ronak2121

I'll have to test the re-encode use case. Does it affect where the issue is happening and what the fix is? I would think this example above shows you that re-encoding has nothing to do with this.

comment:6 in reply to: ↑ 5 Changed 3 months ago by cehoyos

Replying to ronak2121:

I'll have to test the re-encode use case.

Which would taker longer than writing this comment?

Does it affect where the issue is happening and what the fix is?

No, it would only make debugging infinitely simpler.

I would think this example above shows you that re-encoding has nothing to do with this.

Sure, if you say so.

comment:7 follow-up: Changed 3 months ago by ronak2121

So, I just tested this with your idea of trying re-encoding with this output:

ffmpeg -i test.aac -b:a 32k -r:a 44100 -codec libfdk_aac -profile:a aac_he_v2 -bsf:a aac_adtstoasc -hls_time 9.75238095238095 -hls_segment_type fmp4 -hls_flags single_file+append_list+split_by_time -hls_playlist_type vod "test2.m3u8"
ffmpeg version git-2018-06-23-b86c575 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 9.1.0 (clang-902.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-b86c575 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-nonfree
  libavutil      56. 18.102 / 56. 18.102
  libavcodec     58. 20.103 / 58. 20.103
  libavformat    58. 17.101 / 58. 17.101
  libavdevice    58.  4.101 / 58.  4.101
  libavfilter     7. 25.100 /  7. 25.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
[aac @ 0x7fed85000000] Estimating duration from bitrate, this may be inaccurate
Input #0, aac, from 'test.aac':
  Duration: 00:10:13.76, bitrate: 30 kb/s
    Stream #0:0: Audio: aac (HE-AACv2), 44100 Hz, stereo, fltp, 30 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (aac (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
[hls @ 0x7fed84012c00] Opening 'test2.m4s' for writing
Output #0, hls, to 'test2.m3u8':
  Metadata:
    encoder         : Lavf58.17.101
    Stream #0:0: Audio: aac (libfdk_aac) (HE-AACv2), 44100 Hz, stereo, s16, 32 kb/s
    Metadata:
      encoder         : Lavc58.20.103 libfdk_aac
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 3 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
    Last message repeated 2 times
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
[hls @ 0x7fed84012c00] Opening 'test2.m3u8.tmp' for writing
size=N/A time=00:09:44.84 bitrate=N/A speed=  60x

I can confirm the first issue (not having the correct defaultSampleDuration) is present. It looks like the codec issue isn't reproducible when you do a re-encode. I see:

mediastreamvalidator test2.m3u8
mediastreamvalidator: Version 1.2(180612)

[test2.m3u8] Started loading root playlist
[test2.m3u8] Started loading media playlist
[test2.m3u8] parsed media segment count: 30, duration: 302.370
[test2.m3u8] All media files delivered and have end tag, stopping


test2.m3u8


Processed 59 out of 60 segments
Average segment duration: 9.749649
Total segment bitrates (all discontinuities): average: 32.31 kb/s, max: 32.97 kb/s

Discontinuity: sequence: 1, parsed segment count: 59 of 60, duration: 584.979 sec, average: 32.31 kb/s, max: 32.97 kb/s
Track ID: 1
Audio Codec: AAC-HEv2
Audio sample rate: 44100 Hz
Audio channels: 2
Audio channel layout: Stereo (L R)

Last edited 3 months ago by cehoyos (previous) (diff)

comment:8 in reply to: ↑ 7 ; follow-up: Changed 3 months ago by cehoyos

Replying to ronak2121:

I can confirm the first issue (not having the correct defaultSampleDuration) is present. It looks like the codec issue isn't reproducible when you do a re-encode.

Sorry, I am not a native speaker: Could you explain again?
(To me these sentences sound like: The issue is reproducible. It is not reproducible.)

comment:9 Changed 3 months ago by ronak2121

So in summary,

  1. Both issues (bad codec info and sample duration) is reproducible without a reencode.
  2. Doing a reencode seems to fix the bad codec information but not sample duration.

I consider both to be defects as fragmentation should not require a re-encode (it reduces audio quality & increases fragmentation time) and sample duration and codec information should always be correct.

comment:10 Changed 3 months ago by ronak2121

I wonder if this is what the problem is: Apple's HLS Authoring Guide mentions:

" HE-AAC in fMP4 files MUST use explicit signaling of SBR data."

https://developer.apple.com/library/archive/documentation/General/Reference/HLSAuthoringSpec/Requirements.html#//apple_ref/doc/uid/TP40016596-CH2-SW1

comment:11 in reply to: ↑ 8 Changed 3 months ago by ronak2121

Replying to cehoyos:

Replying to ronak2121:

I can confirm the first issue (not having the correct defaultSampleDuration) is present. It looks like the codec issue isn't reproducible when you do a re-encode.

Sorry, I am not a native speaker: Could you explain again?
(To me these sentences sound like: The issue is reproducible. It is not reproducible.)

Hi, will you be able to fix this issue?

comment:12 Changed 2 months ago by stevenliu

I cannot sure if i make a error sample:

but the input audio file duration is 00:01:49.60,
the duration of output after use mediafilesegmenter is 00:01:59.50
Is that correct?

localhost:xxx StevenLiu$ ffmpeg -i test_audio.mp4
ffmpeg version N-83894-g4e3cc4b Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  configuration: --enable-libass --enable-opengl --enable-libx264 --enable-libmp3lame --enable-gpl --enable-nonfree --prefix=/usr/local --enable-libopencv --enable-libtesseract --enable-libspeex --enable-libfreetype --enable-libfontconfig --enable-libfdk-aac --enable-videotoolbox
  libavutil      55. 48.100 / 55. 48.100
  libavcodec     57. 83.100 / 57. 83.100
  libavformat    57. 66.104 / 57. 66.104
  libavdevice    57.  3.100 / 57.  3.100
  libavfilter     6. 76.100 /  6. 76.100
  libswscale      4.  3.101 /  4.  3.101
  libswresample   2.  4.100 /  2.  4.100
  libpostproc    54.  2.100 / 54.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test_audio.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf57.66.104
  Duration: 00:01:49.60, start: 0.000000, bitrate: 31 kb/s
    Stream #0:0(und): Audio: aac (HE-AACv2) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 30 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
At least one output file must be specified
localhost:xxx StevenLiu$ mediafilesegmenter -a -s -r -B test2 -i test2.m3u8 -t 10 test_audio.mp4
Jul 16 2018 16:21:08.168: ISO fragmented mode, forcing segments to start with I-Frame
Jul 16 2018 16:21:08.169: Processing file /Users/StevenLiu/multimedia/ffmpeg/xxx/test_audio.mp4
Jul 16 2018 16:21:08.202: Wrote 0 to 616 to test2.mp4
Jul 16 2018 16:21:08.206: Wrote 616 to 40133 to test2.mp4
Jul 16 2018 16:21:08.207: segment bitrate 31.66 kbits/sec is new max
Jul 16 2018 16:21:08.215: Wrote 40133 to 79650 to test2.mp4
Jul 16 2018 16:21:08.220: Wrote 79650 to 119167 to test2.mp4
Jul 16 2018 16:21:08.225: Wrote 119167 to 158685 to test2.mp4
Jul 16 2018 16:21:08.225: segment bitrate 31.66 kbits/sec is new max
Jul 16 2018 16:21:08.229: Wrote 158685 to 198202 to test2.mp4
Jul 16 2018 16:21:08.236: Wrote 198202 to 237719 to test2.mp4
Jul 16 2018 16:21:08.240: Wrote 237719 to 277237 to test2.mp4
Jul 16 2018 16:21:08.246: Wrote 277237 to 316754 to test2.mp4
Jul 16 2018 16:21:08.251: Wrote 316754 to 356271 to test2.mp4
Jul 16 2018 16:21:08.256: Wrote 356271 to 395789 to test2.mp4
Jul 16 2018 16:21:08.261: Wrote 395789 to 434392 to test2.mp4
Jul 16 2018 16:21:08.261: segment bitrate 31.67 kbits/sec is new max
Jul 16 2018 16:21:08.262: average bit rate is 31.71 kbits/sec - max file bit rate is 31.67 kbits/sec
localhost:xxx StevenLiu$ ffmpeg -i test2.mp4
ffmpeg version N-83894-g4e3cc4b Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  configuration: --enable-libass --enable-opengl --enable-libx264 --enable-libmp3lame --enable-gpl --enable-nonfree --prefix=/usr/local --enable-libopencv --enable-libtesseract --enable-libspeex --enable-libfreetype --enable-libfontconfig --enable-libfdk-aac --enable-videotoolbox
  libavutil      55. 48.100 / 55. 48.100
  libavcodec     57. 83.100 / 57. 83.100
  libavformat    57. 66.104 / 57. 66.104
  libavdevice    57.  3.100 / 57.  3.100
  libavfilter     6. 76.100 /  6. 76.100
  libswscale      4.  3.101 /  4.  3.101
  libswresample   2.  4.100 /  2.  4.100
  libpostproc    54.  2.100 / 54.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 1
    compatible_brands: mp41mp42isomhlsf
    creation_time   : 2018-07-16T08:21:08.000000Z
  Duration: 00:01:59.50, start: 9.904218, bitrate: 29 kb/s
    Stream #0:0(und): Audio: aac (HE-AACv2) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 28 kb/s (default)
    Metadata:
      creation_time   : 2018-07-16T08:21:08.000000Z
      handler_name    : Core Media Audio
At least one output file must be specified
localhost:xxx StevenLiu$

comment:13 Changed 2 months ago by ronak2121

I'm not sure that part is important in this discussion. Have you looked at the issues I call out above where the codec information & defaultSampleDuration in the fMP4 is not being signaled properly?

But at any rate, are you sure that the duration from ffmpeg is accurate? Have you tried running ffmpeg -i test2.mp4 -f null? If so, I'm not sure what Apple is doing to the audio there to change the duration by so much. If you notice, the start: value there is 9.904218 which maps to the offset that you see there. What does that mean in ffmpeg?

comment:14 Changed 7 weeks ago by ronak2121

Can someone please advise on which part of the code I should look at to fix this?

Im relatively new to ffmpeg and don’t have the full background you all have.

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