ffmpeg, MP4, chapters, and, the data stream

[the_steve_randolph]

********** jump to post #10 for the resolution *****************


I have an MP4 that does not have chapters or subtitles (or a data stream). Past experience tells me that when viewing an MP4 with chapters in VLC, VLC adds a ghost subtitle track that when selected only shows the chapter names - and I have learned that this is because VLC seems to be misinterpreting the chapters information in the data stream. And, I know that "-map_metadata 1 -map_chapters 1" is used to add chapters to the output MP4. And, I have found that when I do that, a data stream is typically added to the outout MP4.

When I generate the chapters file with ffmetadata and I add the chapters to that file, the ffmpeg command to add the chapters to the output MP4 adds the correct number of chapters and the correct times, but, it fails to add the chapter titles. VLC shows the titles as "Chapter 0, Chapter 1, etc" and Zoom Player shows the chapters and times, but, no titles. Both jump to the proper times when I click to tell it to go to a chapter. The console display from the ffmpeg command shows that it is seeing all of the chapter information - including the titles. When I look at the ffmpeg output for both MP4s, there is no data stream. I have not worked with ffmpeg for 4-6 months, but, in the past when I added chapters to an MP4, it added a data stream (and I have verified that by checking on an old MP4 today) that seems to have the chapter names.

My understanding is that "-map_metadata 1 -map_chapters 1" handle two separate/different issues when it comes to chapter file and information. I have also tried having "-map 0" in the command line and leaving it out. And, I have commented out each of the lines in the chapters file after the ;FFMETADATA1 line, but, it makes no difference. Google does not seem to know about this issue, so, here I am. What do y'all think is going on?

BTW, I know that I can use other software to add the chapters correctly. But, I want to use ffmpeg and understand what it is doing and not doing.

[ProWo]

Post your full ffmpeg commandline

[Selur]

No clue about VLC or Zoom Player, no clue what your ffmpeg command line looks like, and I have never used ffmetadata.
That said, something like:

ffmpeg -y  -i "<Path to input file>" -i "<path to chapter file>" -map_chapters 1 -c:0 copy -map 0:0 "<path to output file>"

with the chapter file looking like:

;FFMETADATA1
[CHAPTER]
TIMEBASE=1/1000
START=0
END=4999
title=Chapter 1
[CHAPTER]
TIMEBASE=1/1000
START=5000
END=19999
title=Chapter 2
[CHAPTER]
TIMEBASE=1/1000
START=20000
END=49999
title=Chapter 3
[CHAPTER]
TIMEBASE=1/1000
START=50000
END=59999
title=Chapter 4
[CHAPTER]
TIMEBASE=1/1000
START=60000
END=63000
title=Chapter 5

always worked fine for me so far.

Here's the chapter file in mkv format (which I prefer, but ffmpeg doesn't support) for better readability:

CHAPTER01=00:00:00.000
CHAPTER01NAME=Chapter 1
CHAPTER02=00:00:05.000
CHAPTER02NAME=Chapter 2
CHAPTER03=00:00:20.000
CHAPTER03NAME=Chapter 3
CHAPTER04=00:00:50.000
CHAPTER04NAME=Chapter 4
CHAPTER05=00:01:00.000
CHAPTER05NAME=Chapter 5

Maybe that helps,....

Cu Selur

Ps.: I only used a video stream and the chapter info in my example, no audio stream.

[ProWo]

ffmpeg -y  -i "<Path to input file>" -i "<path to chapter file>" -map_chapters 1 -c:0 copy -map 0:0 "<path to output file>"

Works without -map_chapters 1 too.

[the_steve_randolph]

Post your full ffmpeg commandline

ffmpeg -i in.mp4 -i in.txt -map_metadata 1 -map_chapters 1 -c copy out.mp4 2>log.txt

in.txt:

;FFMETADATA1
major_brand=isom
minor_version=512
compatible_brands=isomiso2avc1mp41
encoder=Lavf60.5.100

[CHAPTER]
TIMEBASE=1/1000
START=00000
END=34000
title=Introduction

[CHAPTER]
TIMEBASE=1/1000
START=34000
END=275000
title=My Chapter 1

[CHAPTER]
TIMEBASE=1/1000
START=275000
END=496000
title=My Chapter 2

[CHAPTER]
TIMEBASE=1/1000
START=496000
END=764000
title=My Chapter 3

Console output:

ffmpeg version 2023-04-26-git-e3143703e9-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58.  6.100 / 58.  6.100
  libavcodec     60. 10.100 / 60. 10.100
  libavformat    60.  5.100 / 60.  5.100
  libavdevice    60.  2.100 / 60.  2.100
  libavfilter     9.  5.100 /  9.  5.100
  libswscale      7.  2.100 /  7.  2.100
  libswresample   4. 11.100 /  4. 11.100
  libpostproc    57.  2.100 / 57.  2.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.76.100
  Duration: 01:05:23.41, start: 0.000000, bitrate: 2371 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 2235 kb/s, 29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      handler_name    : ISO Media file produced by XYZ Inc.
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
    Metadata:
      handler_name    : ISO Media file produced by XYZ Inc.
      vendor_id       : [0][0][0][0]
Input #1, ffmetadata, from 'in.txt':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf60.5.100
  Duration: 00:12:44.00, start: 0.000000, bitrate: 0 kb/s
  Chapters:
    Chapter #1:0: start 0.000000, end 34.000000
      Metadata:
        title           : Introduction
    Chapter #1:1: start 34.000000, end 275.000000
      Metadata:
        title           : My Chapter 1
    Chapter #1:2: start 275.000000, end 496.000000
      Metadata:
        title           : My Chapter 2
    Chapter #1:3: start 496.000000, end 764.000000
      Metadata:
        title           : My Chapter 3
Output #0, mp4, to 'out.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf60.5.100
  Chapters:
    Chapter #0:0: start 0.000000, end 34.000000
    Chapter #0:1: start 34.000000, end 275.000000
    Chapter #0:2: start 275.000000, end 496.000000
    Chapter #0:3: start 496.000000, end 764.000000
  Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 2235 kb/s, 29.97 fps, 29.97 tbr, 30k tbn (default)
  Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=    0 fps=0.0 q=-1.0 size=       0kB time=-00:00:00.03 bitrate=  -0.0kbits/s speed=N/A    
frame=32325 fps=0.0 q=-1.0 size=  326656kB time=00:17:58.54 bitrate=2481.1kbits/s speed=2.16e+03x    
frame=61086 fps=61078 q=-1.0 size=  586752kB time=00:33:58.17 bitrate=2358.3kbits/s speed=2.04e+03x    
frame=88069 fps=58686 q=-1.0 size=  825856kB time=00:48:58.50 bitrate=2302.3kbits/s speed=1.96e+03x    
frame=112185 fps=56072 q=-1.0 size= 1079040kB time=01:02:23.21 bitrate=2361.5kbits/s speed=1.87e+03x    
[out#0/mp4 @ 0000021794544fc0] video:1070419kB audio:61303kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.357409%
frame=117583 fps=52731 q=-1.0 Lsize= 1135767kB time=01:05:23.38 bitrate=2371.5kbits/s speed=1.76e+03x

[ProWo]

Try

ffmpeg -i in.mp4 -i in.txt -c copy -map 0 out.mp4

[the_steve_randolph]

Try

ffmpeg -i in.mp4 -i in.txt -c copy -map 0 out.mp4

That worked. But, now I am confused: what is the purpose of "-map_metadata" and "-map_chapters"? When are they supposed to be used? Maybe when converting a MKV to a MP4?

BTW, this works too:

ffmpeg -i in.mp4 -i in.txt -c copy out.mp4

And, this works too:

ffmpeg -i in.mp4 -i in.txt -map_chapters 1 -c copy out.mp4

but I think it is because the "-map-chapters 1" is being ignored.

[Selur]

map_chapters should copy chapters from one input to the output
map_metadata is used to copy metadata from a from an input.
see: https://www.ffmpeg.org/ffmpeg-all.html

[the_steve_randolph]

map_chapters should copy chapters from one input to the output
map_metadata is used to copy metadata from a from an input.
see: https://www.ffmpeg.org/ffmpeg-all.html

In my situation here, my second input file is an ffmetadata file, but, my command did not need either of these two switches. Perhaps one or both switches is used if the first two input files are video files (aka MKV, MP4, AVI, etc)?

[the_steve_randolph]

OK, it seems that "-map_metadata" and "-map_chapters" only do something when there is more than one video file (as opposed to a single video file and a ffmetadata file). And, it also seems that having a single input video file that is a different format (i.e. MKV, MP4, MOV, AVI, etc.) from the output video file does NOT require "-map_metadata" and/or "-map_chapters". Although, I don't know why my orginal command left out the chapter names (maybe the answer is "do something crazy and get crazy results").

Once again, thanks for the help here.