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• How to add dynamic captions with animations on a video in a cross-platform Android & iOS app and export it as a final video ? [closed]

  29 avril, par Danial Qsk

  I'm building a cross-platform mobile app using Flutter (or React Native) where users can :

  


  Add dynamic text captions with animations over a video, similar to TikTok

  


  See these changes in real-time during video playback

  


  Export the video with the animated captions burned into the output (e.g., MP4)

  


  What I’ve implemented so far :

  


  Video playback using video_player in Flutter (or react-native-video).

  


  Captions are rendered using Canvas/UI layer during playback.

  


  Problem : While I can overlay animated text in the UI, I can't figure out how to include these in the exported video. I’m considering using FFmpeg to burn in the captions, but I’m unclear how to integrate it with the animated UI overlays or render them into a final video on both Android and iOS.

  


  What I want to achieve :

  


  Efficient way to render animated text overlays onto a video and export it as a final video file on both Android and iOS.

  


  Maintain good performance for real-time playback and smooth export.

  


  What approaches or processing pipelines could achieve this ?
(For example, rendering the UI layer to an offscreen video, integrating with FFmpeg, or using native rendering techniques.)

  


• Merge commit ’eeaf4f3b87815cbae4c12856cfaafb3a2dae8e0c’

  5 mars 2014, par Michael Niedermayer

  Merge commit ’eeaf4f3b87815cbae4c12856cfaafb3a2dae8e0c’
  * commit ’eeaf4f3b87815cbae4c12856cfaafb3a2dae8e0c’ :
  
    av_vdpau_get_profile : mask out H.264 intra profile flag
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/vdpau.c

• ffmpeg concat : 2nd video stream frozen, no image

  31 juillet 2016, par Azevedo

  I’m trying to concatenate two video streams with the same econding into one :

  ffmpeg -y -f concat -i parts.txt -c copy join.mkv

  parts.txt

  file part1.mkv
  
  file part2.mkv

  ffmpeg will concatenate them but the playback (any player) gives a still image if the playing position corresponds to the 2nd part.
  I tried to switch part1.mkv and part2.mkv to see the results.
  The 1st part (whichever part1 or part2) will play normally but when I seek the playback to the time corresponding the 2nd part the image won’t show, only the audio plays.

  
  
  What happens if i seek the playback to the 2nd part :
  

  UPDATE :
  FULL CONSOLE OUTPUT FOR ffmpeg -y -f concat -i parts.txt -c copy episode.mkv

  ffmpeg version N-81118-gfb91850 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.4.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 28.100 / 55. 28.100
  
    libavcodec     57. 50.100 / 57. 50.100
  
    libavformat    57. 44.100 / 57. 44.100
  
    libavdevice    57.  0.102 / 57.  0.102
  
    libavfilter     6. 49.100 /  6. 49.100
  
    libswscale      4.  1.100 /  4.  1.100
  
    libswresample   2.  1.100 /  2.  1.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [matroska,webm @ 000000000242bd40] Auto-inserting h264_mp4toannexb bitstream filter
  
  Input #0, concat, from 'parts.txt':
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: h264 (High), yuv420p(tv, bt709), 1280x720, SAR 1:1 DAR 16:9, 23.97 fps, 23.97 tbr, 1k tbn, 47.95 tbc
  
      Metadata:
  
        BPS             : 1023638
  
        BPS-eng         : 1023638
  
        _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  
        DURATION-eng    : 00:23:17.980000000
  
        NUMBER_OF_FRAMES: 33518
  
        NUMBER_OF_FRAMES-eng: 33518
  
        NUMBER_OF_BYTES : 178878340
  
        NUMBER_OF_BYTES-eng: 178878340
  
        _STATISTICS_WRITING_APP: mkvmerge v9.3.1 ('Mask Machine') 64bit
  
        _STATISTICS_WRITING_APP-eng: mkvmerge v9.3.1 ('Mask Machine') 64bit
  
        _STATISTICS_WRITING_DATE_UTC: 2016-07-30 17:28:29
  
        _STATISTICS_WRITING_DATE_UTC-eng: 2016-07-30 17:28:29
  
        _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  
        DURATION        : 00:22:13.164000000
  
  [matroska @ 0000000000e7c920] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
  
  Output #0, matroska, to 'episode.mkv':
  
    Metadata:
  
      encoder         : Lavf57.44.100
  
      Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p(tv, bt709), 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 23.97 fps, 23.97 tbr, 1k tbn, 1k tbc
  
      Metadata:
  
        BPS             : 1023638
  
        BPS-eng         : 1023638
  
        _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  
        DURATION-eng    : 00:23:17.980000000
  
        NUMBER_OF_FRAMES: 33518
  
        NUMBER_OF_FRAMES-eng: 33518
  
        NUMBER_OF_BYTES : 178878340
  
        NUMBER_OF_BYTES-eng: 178878340
  
        _STATISTICS_WRITING_APP: mkvmerge v9.3.1 ('Mask Machine') 64bit
  
        _STATISTICS_WRITING_APP-eng: mkvmerge v9.3.1 ('Mask Machine') 64bit
  
        _STATISTICS_WRITING_DATE_UTC: 2016-07-30 17:28:29
  
        _STATISTICS_WRITING_DATE_UTC-eng: 2016-07-30 17:28:29
  
        _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
  
        DURATION        : 00:22:13.164000000
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [matroska,webm @ 0000000002605dc0] Auto-inserting h264_mp4toannexb bitstream filterpeed=1.87e+003x
  
  frame=56417 fps=47467 q=-1.0 Lsize=  304604kB time=00:39:13.05 bitrate=1060.5kbits/s speed=1.98e+003x
  
  video:304191kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.135798%