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• How to capture device input with ffmpeg in C ?

  24 mai 2019, par Yi Lin Liu

  I am trying to use ffmpeg in my C code to capture device input, like screen and audio record. I have looked through their official documentation and wiki, but the API documentation is not really well explained compare to the command line usage.

  According to the documentation, if I want to record audio with alsa on linux I could, for example

  ffmpeg -f alsa -i hw:&lt;#card>,&lt;#device> -t <seconds> out.wav
  
  </seconds>

  I want to use the C API to do the same thing, any idea ?

• ffmpeg, we reported the error of av_interleaved_write_frame() : End of fileB Error writing trailer of rtmps ://live-api-s.facebook.com:443/rtmp/*

  21 octobre 2022, par yong zhang

  We want to implement such a small function, using webrtc technology on the web side to push the stream to the webrtc service of SRS, and then push the rtmp stream of SRS to the go live of facebook through ffmpeg to push the live broadcast. But we encountered a problem. When we forwarded and pushed the stream with ffmpeg, we reported the error of av_interleaved_write_frame() : End of fileB Error writing trailer of rtmps ://live-api-s.facebook.com:443/rtmp/. Please help and guide the heroes to see where the problem may occur.
The command we executed is : ./ffmpeg -threads 2 -thread_queue_size 9512 -re -i "rtmp ://xxx.xxx.xxx:1935/live/" -max_muxing_queue_size 1024 -force_key_frames "expr:gte (t,n_forced2)" -vf crop=in_w:in_w9/16,scale=1280:720 -reorder_queue_size 4000 -max_delay 10000000 -c:v libx264 -preset veryfast -b:v 3000k -maxrate 1500k -bufsize 4000k -g 50 -c:a aac -ac 2 -ar 48000 -f flv -r 30 -flvflags no_duration_filesize "rtmps ://live-api-s.facebook.com:443/rtmp/"
The ffmpeg version is : 4.13 and above all the same error.
SRS version : 5.56

  


• ffmpeg transcoding : Metallic distorsion on macOS

  10 septembre 2024, par Xavi

  I am following ffmpeg's transcoding.c example to record audio and video from my input devices into an mp4 output file with H264 and AAC as codecs. I have no issues with the video and the audio transcoding works correctly on Windows.

  


  However, on macOS I have an issue with any input device other than the internal microphone of my laptop : the audio comes out distorted and sounding noisy and metallic (sample recording claps : https://file.io/nEn8MXHUAUQ2). I went through the input and output parameters for the filter several times, checked the values, but there must be something I'm missing. And I can't explain why it works on Windows with the same devices.

  


  Has anyone run into a similar problem before ? Any idea where I should start looking at ?

  


  Additional comments :

  


  

  1. While the Macbook's internal microphone (the only one that works) has only one channel, the other microphones I have available are stereo, so I can't say for sure that that's where the problem is.

  


  2. I also tested it on a macbook mini, with the same results.

  


  3. ffmpeg 6.1.1, MacOs 14.5

  


  4. Input filter arguments : time_base=1/1000000:sample_rate=48000:sample_fmt=1:channel_layout=stereo

  


  5. Output filter arguments : setpts=PTS-STARTPTS,aresample=48000:async=1:out_sample_fmt=8:out_chlayout=stereo,asetnsamples=n=1024