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• How would I add an audio channel to an rtsp stream ?

  9 septembre 2022, par PlayerWet

  Good companions. It turns out that my Raspberry does not give more than itself when it comes to joining video with audio at good quality and sending it by rtsp. But I think I could send the video in rtsp format and then the audio in mp3, but I would need to join it again on another computer (nas Debian) on my home lan where I have the Shinobi program (security camera manager) installed.

  


  I would need something that can somehow grab the rtsp stream and another mp3 audio and merge them into a new rtsp stream. Is this possible ? or is it a crazy idea.

  


  On the one hand I send this, which is the transmission of the camera by rtsp through v4l2rtspserver :

  


  v4l2rtspserver -H 1080 -W 1920 -F 25 -P 8555 /dev/video0


  


  And separately I send an audio in mp3 with sound from a usb microphone through ffmpeg :

  


  ffmpeg -ac 1 -f alsa -i hw:1,0 -acodec libmp3lame -ab 32k -ac 1 -f rtp rtp://192.168.1.77:12348


  


  My idea is to put both things together on a nas server in a new rtsp stream (or another idea).

  


  But I don't know if with ffmpeg I can capture the video from an rtsp video stream and then be able to join it with the mp3 audio and form another new rtsp stream.

  


  Merge these two streams into one and reassemble an rtsp :

  


  rtsp://192.168.1.57:8555/unicast

rtp://192.168.1.77:12348


  


  I have tried this way but it gives me an error :

  


  ffmpeg \
    -i rtsp://192.168.1.57:8555/unicast \
    -i rtp://192.168.1.37:12348 \
    -acodec copy -vcodec libx264 \
    -f rtp_mpegts "rtp://192.168.1.77:5000?ttl=2"


  


  Error :

  


  [h264 @ 0x55ac6acaf4c0] non-existing PPS 0 referenced
    Last message repeated 1 times
[h264 @ 0x55ac6acaf4c0] decode_slice_header error
[h264 @ 0x55ac6acaf4c0] no frame!
[h264 @ 0x55ac6acaf4c0] non-existing PPS 0 referenced
    Last message repeated 1 times
[h264 @ 0x55ac6acaf4c0] decode_slice_header error
[h264 @ 0x55ac6acaf4c0] no frame!
[h264 @ 0x55ac6acaf4c0] non-existing PPS 0 referenced
    Last message repeated 1 times


  


  What am I doing wrong ?

  


• How to efficiently convert images to a video in `ffmpeg`

  9 septembre 2022, par tawfikboujeh

  I discovered squoosh and found out that it does crazy compression on images,

  


  Squoosh only works on images and i wanted to scale it to work on videos.

  


  I then wrote this script to convert the video to a set of images that I'll squoosh and then reconstitute to a video again using the almighty ffmpeg.

  


  mkdir out ; rm -rf ./out/*
ffmpeg -i input.mp4 -r 25 buffer.mp4 # for a reason, i needed to create a buffer, this is hacky, but whatever.
ffmpeg -i buffer.mp4 -vf fps=25 out/out%d.png # convert the image into images
squoosh-cli --mozjpeg '{quality: 75}' out/*.png # compress
FRAMERATE=$(ffmpeg -i buffer.mp4 2>&1 | sed -n "s/.*, \(.*\) fp.*/\1/p") # get the framerate from buffer video
ffmpeg -framerate $FRAMERATE -i out/out%d.jpg output.mp4 # reconstitute the video knowing the framerate and having the compressed images


  


  the images are 90% smaller but the video has a bigger size than the original one.

  


  benchmarks :

  


  for the images :

  


  1.jpeg : 98 KB on disk
1.png : 1,7 MB on disk 


  


  for the videos :

  


  input.mp4 : 20 Mb on disk
buffer.mp4 : 21 Mb on disk
output.mp4 : 19 Mb on disk


  


  Any idea on how to make ffmpeg pack the images to an acceptable size ?

  


• Does FFmpeg not support G723_1 transmit at 5.3k bitrate？

  8 octobre 2022, par Zih

  Recently I needed to implement the 5.3k bitrate transmission of the G723.1 protocol on an VoIP phone, but I found that in the g723_1enc.c language file under the ffmpeg's libavcodec folder, there is a description of the picture below, the image is from Github.enter image description here

  


  This code is in the "g723_1_encode_init AVCodecContext *avctx", does this mean that ffmpeg does not support the G723.1 protocol to transmit at 5.3 bps ? What kind of changes might I be able to make it support ? Because I want it to be a choice between 6.3k and 5.3k. Is this achievable ? I would appreciate any advice.

  


  p.s.I'm guessing that a drastic revision of the code will be needed, I just graduated from college and have recently entered the field, please give me some advice