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• Adding multiple audio tracks and subtitles to dash manifest (mpd) with ffmpeg

  21 novembre 2020, par knona

  I'm trying to create a website to stream some videos. For each video, I extract video, audio and subtitles in 3 different folders. It happens that a video has multiple audio tracks and multiple subtitles. I did a lot of research and I don't know how to add all of them in the manifest. Right now, I use this command :

  



  ffmpeg -f webm_dash_manifest \
-i video1.mp4 -f webm_dash_manifest \
-i video2.mp4 -f webm_dash_manifest \
-i audio1.webm -f webm_dash_manifest \
-i audio2.webm -f webm_dash_manifest \
-i subtitles.vtt \
-c copy -map 0 -map 1 -map 2 -map 3 \
-f webm_dash_manifest -adaptation_sets "id=0,streams=v id=1,streams=a" manifest.mpd


  



  My two videos have different resolutions and bitrates, and it works perfectly. But I don't get any subtitles and my two audio tracks are considered like one same audio track which has two different bitrates (just like videos). I think I should have many adaptation_sets, but I don't know how to create them.

  



  How can I create that manifest the right way ?

  


• Converting AAC stream to DASH MP4 with high fragment length precision

  5 mars 2017, par vdudouyt

  For my HTML5 project I need to create a fragmented MP4 file with a single audio stream (no video), each fragment of which has a duration of exactly 0.1 second.

  Accordingly to ffmpeg docs, you can accomplish that by passing a value in microseconds with ’-frag_duration’ - which I found to be working and playable with HTML5 MediaSource API :

  $ ffmpeg -y -i input.aac -c:a libfdk_aac -b:a 64k -level:v 13 -r 25 -strict experimental -movflags empty_moov+default_base_moof -frag_duration 100000 output.mp4

  As we have a 210 second audio split up by 0.1s fragments, I expect that in output.mp4 we’d have 2100 fragments, hence 2100 moof atoms. But, upon inspecting it I’ve figured out that we only have 1811 moof atoms - which means that some (or maybe even all) fragments are bigger than expected :

  $ python ~/git/mp4viewer/src/showboxes.py output.mp4 |grep moof|wc -l
  
  1811

  Could anybody tell me what’s wrong, and how could I accomplish what I want ?

  Right now my assumption is that during an encoding I have AAC frame length which is not a multiple of 0.1s, hence ffmpeg has no chance to produce the fragments that are strictly equal to 0.1s but I’m not sure. If somebody can confirm that - and let me know a way to explicitly set AAC frame_size in FFMPEG (I couldn’t find anything like that in the docs), or completely disprove this - it would be also highly appreciated.

• FFMPEG Picture in picture with DASH

  24 mai 2022, par Macster

  I'm using FFMPEG to transcode a video into different resolutions and it's working fine. But now I want to merge two videos picture in picture, as one video, which then has to be transcoded into different resolutions.

  


  The command below is what I've got so far. Unfortunately, it works only for the 170p resolution. If I switch the player to 720p the overlay video is gone.

  


  I guess I have to use some kind of naming scheme for the merging files and the different resolutions, so FFMPEG can differentiate between them. But how am I going to do that ?

  


  FFMPEG Command

  


  ffmpeg \
-re \
-i "input.webm" \
-i "overlay.webm" \
-filter_complex "[1]scale=iw/3:-1[pip];[0][pip]overlay=W-w-10:10:shortest=1[v];[0:a][1:a]amerge[a]" \
-r 30 \
-usage lowlatency \
-qp_b 1 \
-quality ultrafast \
-level 2.0 \
-map "[v]" \
-map "[a]" \
-map 0 \
-c:a aac \ 
-c:v h264_qsv \
-b:v:1 1800k \
-s:v:1 1280x720 \
-b:v:0 300k \
-s:v:0 320x170 \
-profile:v:0 main \
-profile:v:1 main \
-bf 1 \
-keyint_min 30 \
-g 30 \
-sc_threshold 1 \
-b_strategy 0 \
-ar:a:1 96000 \
-seg_duration 1 \
-remove_at_exit 0 \
-streaming 1 \
-window_size 10 \
-adaptation_sets "id=0,streams=v id=1,streams=a" \
-utc_timing_url https://time.akamai.com/?iso \
-live 1 \
-f dash "manifest.mpd"