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• Combining two multi-channel streams into one

  31 mars 2023, par Christiaan Roselaar

  Hi to all you FFmpeg Guru's.

  


  I'm doing my best to combine two incoming webstreams on my server. One of them containing two (2) mono audio-channels, the other five (5). The objective is to create one stream containing seven (7) channels, to be routed directly to the hardware.

  


  At the two transmission-origins, host_a and host_b, the streams are generated as follows :

  


  host_a : $ ffmpeg -hide_banner -loglevel error -f jack -channels 1 -i Tonmeister_mic1 -f jack -channels 1 -i Tonmeister_mic2 -nostdin -filter_complex "[0:a][1:a]amerge=inputs=2[a]" -map "[a]" -codec:a libopus -b:a 128k -vbr on -packet_loss 10 -fec on -compression_level 10 -frame_duration 20 -application audio -f mpegts udp ://X.X.X.X:yyyy &

  


  host_b : $ ffmpeg -hide_banner -loglevel error -f jack -channels 1 -i Tonmeister_mic1 -f jack -channels 1 -i Tonmeister_mic2 -f jack -channels 1 -i Tonmeister_mic3 -f jack -channels 1 -i Tonmeister_mic4 -f jack -channels 1 -i Tonmeister_mic5 -nostdin -filter_complex "[0:a][1:a][2:a][3:a][4:a]amerge=inputs=5[a]" -map "[a]" -codec:a libopus -b:a 128k -vbr on -packet_loss 10 -fec on -compression_level 10 -frame_duration 20 -application audio -f mpegts udp ://X.X.X.X:zzzz &

  


  The streams do seem to get in allright :

  


  cjr-macbook : CJR$ ffprobe -hide_banner -i udp ://127.0.0.1:yyyy
Input #0, mpegts, from 'udp ://127.0.0.1:yyyy' :
Duration : N/A, start : 4759.783900, bitrate : N/A
Program 1
Metadata :
service_name : Service01
service_provider : FFmpeg
Stream #0:0[0x100] : Audio : opus (Opus / 0x7375704F), 48000 Hz, stereo, fltp

  


  cjr-macbook : CJR$ ffprobe -hide_banner -i udp ://127.0.0.1:zzzz
Input #0, mpegts, from 'udp ://127.0.0.1:zzzz' :
Duration : N/A, start : 4856.559000, bitrate : N/A
Program 1
Metadata :
service_name : Service01
service_provider : FFmpeg
Stream #0:0[0x100] : Audio : opus (Opus / 0x7375704F), 48000 Hz, 5.0, fltp

  


  However, I just cannot figure out how to combine the seven (7) channels present in these two incoming streams into one seven-channel stream.

  


  At the receiving end I tried various commands, amongst others

  


  cjr-macbook : CJR$ ffmpeg -hide_banner -loglevel verbose -i udp ://127.0.0.1:yyyy -i udp ://127.0.0.1:zzzz -filter_complex "[0:a]channelsplit=channel_layout=stereo[b]" ;"[1:a]channelsplit=channel_layout=5.0[c]" ;"[b][c]amerge=inputs=7[d]" -map "[d]" sevenchannels.wav

  


  Any help appreciated !

  


• FFmpeg ; combining two multi-channel streams into one

  30 mars 2023, par Christiaan Roselaar

  Hi to all you FFmpeg Guru's.

  


  I'm doing my best to combine two incoming webstreams on my server. One of them containing two (2) mono audio-channels, the other five (5). The objective is to create one stream containing seven (7) channels, to be routed directly to the hardware.

  


  At the two transmission-origins, host_a and host_b, the streams are generated as follows :

  


  host_a : $ ffmpeg -hide_banner -loglevel error -f jack -channels 1 -i Tonmeister_mic1 -f jack -channels 1 -i Tonmeister_mic2 -nostdin -filter_complex "[0:a][1:a]amerge=inputs=2[a]" -map "[a]" -codec:a libopus -b:a 128k -vbr on -packet_loss 10 -fec on -compression_level 10 -frame_duration 20 -application audio -f mpegts udp ://X.X.X.X:yyyy &

  


  host_b : $ ffmpeg -hide_banner -loglevel error -f jack -channels 1 -i Tonmeister_mic1 -f jack -channels 1 -i Tonmeister_mic2 -f jack -channels 1 -i Tonmeister_mic3 -f jack -channels 1 -i Tonmeister_mic4 -f jack -channels 1 -i Tonmeister_mic5 -nostdin -filter_complex "[0:a][1:a][2:a][3:a][4:a]amerge=inputs=5[a]" -map "[a]" -codec:a libopus -b:a 128k -vbr on -packet_loss 10 -fec on -compression_level 10 -frame_duration 20 -application audio -f mpegts udp ://X.X.X.X:zzzz &

  


  The streams do seem to get in allright :

  


  cjr-macbook : CJR$ ffprobe -hide_banner -i udp ://127.0.0.1:yyyy
Input #0, mpegts, from 'udp ://127.0.0.1:yyyy' :
Duration : N/A, start : 4759.783900, bitrate : N/A
Program 1
Metadata :
service_name : Service01
service_provider : FFmpeg
Stream #0:0[0x100] : Audio : opus (Opus / 0x7375704F), 48000 Hz, stereo, fltp

  


  cjr-macbook : CJR$ ffprobe -hide_banner -i udp ://127.0.0.1:zzzz
Input #0, mpegts, from 'udp ://127.0.0.1:zzzz' :
Duration : N/A, start : 4856.559000, bitrate : N/A
Program 1
Metadata :
service_name : Service01
service_provider : FFmpeg
Stream #0:0[0x100] : Audio : opus (Opus / 0x7375704F), 48000 Hz, 5.0, fltp

  


  However, I just cannot figure out how to combine the seven (7) channels present in these two incoming streams into one seven-channel stream.

  


  At the receiving end I tried various commands, amongst others

  


  cjr-macbook : CJR$ ffmpeg -hide_banner -loglevel verbose -i udp ://127.0.0.1:yyyy -i udp ://127.0.0.1:zzzz -filter_complex "[0:a]channelsplit=channel_layout=stereo[b]" ;"[1:a]channelsplit=channel_layout=5.0[c]" ;"[b][c]amerge=inputs=7[d]" -map "[d]" sevenchannels.wav

  


  Any help appreciated !

  


• 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