Opened 7 months ago
Last modified 6 months ago
#11030 new defect
Remuxing a damaged MP4 increases file size noticeably
Reported by: | PumaD | Owned by: | |
---|---|---|---|
Priority: | normal | Component: | avcodec |
Version: | git-master | Keywords: | aac |
Cc: | PumaD, MasterQuestionable | Blocked By: | |
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
Got a slightly damaged 1.9 GiB MP4 file. When remuxing with ffmpeg the resulting file is a whole 224 MiB larger than before (from 1.9 GiB to 2.2 GiB).
Remuxing the file with mkvtoolnix instead reduces the file size marginally.
(https://gitlab.com/mbunkus/mkvtoolnix; mkvmerge --output out.mkv slightly-damaged-audio-stops-at-00-43-05.mp4
)
The effect on the sample below is a much more modest increase of ~30 MiB, but it does illustrate the problem.
Sample (from #11028):
https://streams.videolan.org/ffmpeg/incoming/11028/slightly-damaged-audio-stops-at-00-43-05.mp4 (~ 1 GiB)
Note: NSFW
How to reproduce:
$ ffmpeg -i slightly-damaged-audio-stops-at-00-43-05.mp4 -c copy out.mkv ffmpeg version N-115363-g3146b77a7d Copyright (c) 2000-2024 the FFmpeg developers built with gcc 14.1.1 (GCC) 20240507 configuration: libavutil 59. 19.100 / 59. 19.100 libavcodec 61. 5.104 / 61. 5.104 libavformat 61. 3.103 / 61. 3.103 libavdevice 61. 2.100 / 61. 2.100 libavfilter 10. 2.102 / 10. 2.102 libswscale 8. 2.100 / 8. 2.100 libswresample 5. 2.100 / 5. 2.100 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x624f2ebf8840] Sample size 3043950162 is too large [h264 @ 0x624f2ebf9800] concealing 1691 DC, 1691 AC, 1691 MV errors in I frame Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'slightly-damaged-audio-stops-at-00-43-05.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf57.62.100 Duration: 01:28:36.03, start: 0.000000, bitrate: 1577 kb/s Stream #0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(progressive), 960x720 [SAR 1:1 DAR 4:3], 3028 kb/s, 29.93 fps, 30 tbr, 90k tbn (default) Metadata: handler_name : VideoHandler vendor_id : [0][0][0][0] Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 93 kb/s (default) Metadata: handler_name : SoundHandler vendor_id : [0][0][0][0] Stream mapping: Stream #0:0 -> #0:0 (copy) Stream #0:1 -> #0:1 (copy) Output #0, matroska, to 'out.mkv': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf61.3.103 Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(progressive), 960x720 [SAR 1:1 DAR 4:3], q=2-31, 3028 kb/s, 29.93 fps, 30 tbr, 1k tbn (default) Metadata: handler_name : VideoHandler vendor_id : [0][0][0][0] Stream #0:1(und): Audio: aac (LC) ([255][0][0][0] / 0x00FF), 44100 Hz, stereo, fltp, 93 kb/s (default) Metadata: handler_name : SoundHandler vendor_id : [0][0][0][0] Press [q] to stop, [?] for help [h264 @ 0x624f2ef99e00] Invalid NAL unit size (-720787532 > 47705). [h264 @ 0x624f2ef99e00] missing picture in access unit with size 47709 [h264 @ 0x624f2ef99e00] Invalid NAL unit size (1049218 > 11473).31e+03x [h264 @ 0x624f2ef99e00] missing picture in access unit with size 11477 [h264 @ 0x624f2ef99e00] Invalid NAL unit size (722808771 > 10603). [h264 @ 0x624f2ef99e00] missing picture in access unit with size 10607 [h264 @ 0x624f2ef99e00] Invalid NAL unit size (526767940 > 14657).+03x [h264 @ 0x624f2ef99e00] missing picture in access unit with size 14661 [h264 @ 0x624f2ef99e00] Invalid NAL unit size (1063190835 > 51). [h264 @ 0x624f2ef99e00] missing picture in access unit with size 6615 Truncating packet of size 268435713 to 355012330kbits/s speed=1.48e+03x [mov,mp4,m4a,3gp,3g2,mj2 @ 0x624f2ebf8840] Packet corrupt (stream = 1, dts = 113707010). [in#0/mov,mp4,m4a,3gp,3g2,mj2 @ 0x624f2ebf8580] corrupt input packet in stream 1 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x624f2ebf8840] Packet corrupt (stream = 0, dts = 240368850). [h264 @ 0x624f2ef99e00] Invalid NAL unit size (15412 > 629). [h264 @ 0x624f2ef99e00] missing picture in access unit with size 639 [in#0/mov,mp4,m4a,3gp,3g2,mj2 @ 0x624f2ebf8580] corrupt input packet in stream 0 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x624f2ebf8840] stream 0, offset 0x3e803ab9: partial file [out#0/matroska @ 0x624f2ebfabc0] video:988025KiB audio:64471KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.138273% size= 1053952KiB time=00:44:30.79 bitrate=3232.7kbits/s speed=1.45e+03x
Attachments (1)
Change History (19)
follow-up: 2 comment:1 by , 7 months ago
Cc: | added |
---|---|
Component: | undetermined → avformat |
comment:2 by , 7 months ago
Replying to MasterQuestionable:
͏ Try "-map_metadata -1 -map_chapters -1"?
That only saves 155 bytes. No change in the terminal output either. The full command I tested was:
ffmpeg -i slightly-damaged-audio-stops-at-00-43-05.mp4 -c copy -map_metadata -1 -map_chapters -1 out.mkv
comment:3 by , 7 months ago
͏ Try also "-ignore_editlist"?
͏ https://trac.ffmpeg.org/ticket/11027#comment:4
comment:4 by , 7 months ago
No effect whatsoever. (For future readers: It needs to be used like -ignore_editlist true
)
comment:5 by , 7 months ago
Component: | avformat → avcodec |
---|---|
Keywords: | h264 added |
͏ "-ignore_editlist 1" also OK.
͏ Caveat it's supposed to be used as input option (before ͏"-i").
͏ (using which as output doesn't cause failure... and seem no-op)
͏ Change the "Component" and "Keywords" back if:
͏ |*| You did it wrong.
͏ |*| ͏"-ignore_editlist" indeed doesn't help.
comment:6 by , 7 months ago
Yeah, of course I did it wrong but it still only saves 4 bytes (+ the 155 bytes from before).
I'm assuming you meant so say "indeed does help" and will leave Component
and Keywords
untouched.
comment:7 by , 7 months ago
͏ Last to make sure:
͏ Try remuxing with only audio/video for each.
͏ (using "-an" "-vn" respectively; or like [ https://trac.ffmpeg.org/ticket/11005#comment:18 ], but with ͏"-map")
comment:8 by , 7 months ago
It's the audio stream.
The audio-only file created by ffmpeg with:
ffmpeg -i slightly-damaged-audio-stops-at-00-43-05.mp4 -c copy -vn slightly-damaged-audio-stops-at-00-43-05-audio.mka
is 63.7 MiB. The audio-only file created by mkvtoolnix is just 30.4 MiB.
The video-only files are reasonably close at 965.5 MiB (ffmpeg) vs 965.3 MiB (mkvtoolnix).
Tested also on the full file where the audio-only files are 285.9 MiB (ffmpeg) vs 60.2 MiB (mkvtoolnix).
comment:9 by , 7 months ago
Keywords: | aac added; h264 removed |
---|
͏ Note also:
͏ https://trac.ffmpeg.org/ticket/11005#comment:9
͏ What happens when further remuxing the problematic audio? (both FFmpeg, MKVToolNix)
comment:10 by , 7 months ago
full_video.mp4
to audio-only.mka
=> 285.9 MiB
full_video.mp4
to audio-only.mp4
=> 285.6 MiB
audio-only.mp4
with ffmpeg to MKV => 285.9 MiB
audio-only.mp4
with ffmpeg to MP4 => 285.6 MiB
audio-only.mp4
with mkvtoolnix to MKV => 29.5 MiB
audio-only.mka
with ffmpeg to MKV => 29.9 MiB
audio-only.mka
with ffmpeg to MP4 => 29.6 MiB
audio-only.mka
with mkvtoolnix to MKV => 285.5 MiB
Remuxing of audio-only.mka
with ffmpeg shows this warning, which is not present when remuxing audio-only.mp4
:
[matroska,webm @ 0x56bfff0f1840] Invalid length 0x10000105 > 0x10000000 for element with ID 0xA3 at 0x1dc7629
Truncating packet of size 104572254 to 49047102
That's likely related to #11028 as the audio for the full file should be ~60 MiB, not just ~30 MiB.
follow-up: 12 comment:11 by , 7 months ago
͏ Caveat implicit logic error in your statement:
͏ "audio-only.mka" definition overlap. (clean-up preferable)
͏ 1 more test:
͏ Does zipping the problematic audios (separately for each) yield significant compression? (great size reduction)
comment:12 by , 7 months ago
Replying to MasterQuestionable:
Caveat implicit logic error in your statement:
͏"audio-only.mka" definition overlap. (clean-up preferable)
I don't see any error. Could you elaborate on what you think is wrong?
͏ 1 more test:
͏ Does zipping the problematic audios (separately for each) yield significant compression? (great size reduction)
No, zipping them saves only a couple hundred KiB each. Nothing that would suggest large blocks of identical bytes.
comment:13 by , 7 months ago
[[
͏ "audio-only.mka" with FFmpeg to MKV => 29.9 MiB
͏ ...
͏ "audio-only.mka" with MKVToolNix to MKV => 285.5 MiB
]]
͏ How?
comment:14 by , 6 months ago
Answering the "how" is beyond my pay grade, but it's definitely what I'm seeing and not just a typo.
comment:15 by , 6 months ago
͏ I believe the 1st "audio-only.mka" is that implicitly derived from:
͏ "audio-only.mp4" with MKVToolNix to MKV => 29.5 MiB
͏ While the 2nd is:
͏ "full_video.mp4" to "audio-only.mka" => 285.9 MiB [ With FFmpeg. ]
comment:16 by , 6 months ago
No, I've double checked that they've been generated from the same audio-only.mka
. Here's the output of the full process: https://pastebin.com/5XjGHj5z
comment:17 by , 6 months ago
͏ It appears remuxing twice to Matroska (with FFmpeg) causes the truncation in the 2nd run.
͏ What happens when "-c copy" twice with MP4?
comment:18 by , 6 months ago
That would be this line from the table above:
audio-only.mp4
with ffmpeg to MP4 => 285.6 MiB
by , 6 months ago
Attachment: | audio-only.mka.txt added |
---|
͏ Filtered from: https://pastebin.com/raw/5XjGHj5z
͏ Try "-map_metadata -1 -map_chapters -1"?