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• How can ffmpeg concat MP3s with full metadata incl. cover art ?

  13 décembre 2022, par TEN

  Audio books inconveniently split into dozens of MP3s (with spaces in their names) should be merged into one MP3 in a subdirectory (in which ffmpeg version 4.2.7-0ubuntu0.1 is invoked), without time-consuming and possibly degrading conversions, reliably preserving all metadata incl. cover art (present and similar in all MP3s of a title, their differences being significant only in lengths and track numbers).

  


  However, rather than picking the latter from the first input MP3, the https://trac.ffmpeg.org/wiki/Concatenate#protocol loses the cover art, the https://trac.ffmpeg.org/wiki/Concatenate#demuxer documented as more flexible even loses all metadata :

  


  ffmpeg -v verbose -f concat -safe 0 -i <(printf "file '$PWD/%s'\n" ../in\ track*.mp3) -c copy "out.mp3"
...
Input #0, concat, from '/dev/fd/63':
Duration: N/A, start: 0.000000, bitrate: 192 kb/s
Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 192 kb/s
Stream #0:1: Video: png, 1 reference frame, rgba(pc), 300x300, 90k tbr, 90k tbn, 90k tbc
Metadata:
title           : 12ae3b8152eaf255ae0315c59400c540.png
comment         : Cover (front)
...
Output #0, mp3, to 'out.mp3':
Metadata:
TSSE            : Lavf58.29.100
Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 192 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (copy)
...
[AVIOContext @ 0x561459f3dac0] Statistics: 1958050 bytes read, 0 seeks
[mp3 @ 0x561459f3f900] Skipping 0 bytes of junk at 110334.
[mp3 @ 0x561459f3f900] Estimating duration from bitrate, this may be inaccurate
No more output streams to write to, finishing.
size=   75793kB time=00:53:03.12 bitrate= 195.1kbits/s speed= 636x
video:0kB audio:75793kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000865%
Input file #0 (/dev/fd/63):
Input stream #0:0 (audio): 121847 packets read (77611658 bytes);
Input stream #0:1 (video): 40 packets read (4358440 bytes);
Total: 121887 packets (81970098 bytes) demuxed
Output file #0 (out.mp3):
Output stream #0:0 (audio): 121847 packets muxed (77611658 bytes);
Total: 121847 packets (77611658 bytes) muxed
[AVIOContext @ 0x561459ef6700] Statistics: 2 seeks, 298 writeouts
[AVIOContext @ 0x561459f39e40] Statistics: 2006324 bytes read, 0 seeks
[AVIOContext @ 0x561459ee0300] Statistics: 5040 bytes read, 0 seek


  


  The metadata incl. cover PNG as detected (as single-frame "video") should end up in the output MP3, but doesn't (even when adding -movflags use_metadata_tags possibly intended for other formats).

  


  -metadata track="1/1" (or without the /1 ?) may be required as the first input MP3 sometimes wrongly starts at a higher number.

  


  How do I make sure no metadata (incl. image) other than track numbers is lost when concatenating MP3s (by protocol or demuxer, from a set of input files with spaces in their names and a wildcard to match across track numbers) ?

  


• Using FFMPEG, how do we add subtitles in the black bar area or under the video ?

  26 septembre 2020, par DunceDancer

  I followed these steps :

  


  


  1. Added the black bars

     


     -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080 :(ow-iw)/2 :(oh-ih)/2,setsar=1" Source :How to add black borders to video

     


  


  2. Added the subtitles ("burned" it into the video)

     


     ffmpeg -i "imput.mp4" -lavfi "subtitles=subtitles.srt:force_style='Alignment=0,OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,Fontsize=18,MarginL=5,MarginV=25'" -crf 1 -c:a copy "output.mp4" Source : ffmpeg subtitles alignment and position

     


  


  


  Now I am stuck as to how to place the subtitles under the video or in the black screen.

  


  Edit : Screenshot added to clarify

  


  Screenshot of the Problem

  


• FFMPEG Replacing black color fragments with alpha channel transperency

  31 décembre 2017, par kostya572

  I have "file.mov" video. It has a lot of blank black color fragments that have different durations.

  I need to replace black color fragments that durates more than 5 seconds with transparency ? Is that possible to add some alpha channel for that purpose ?