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• ffmpeg splits video with differents segments size

  22 mai 2018, par Rafael Lima

  im trying to split a video in segments with same lenght using ffmpeg

  ffmpeg -y -i teste.mp4 -map 0 -segment_time 10 -f segment -c:v libx264 -preset veryfast -crf 24 -tune film -vf "drawtext=text='teste':start_number=0:x=0:y=0" -an teste\out%d.mp4

  the input file is 3minutes

  in the output folder i get several files each have a duration between 8 and 13 seconds.

  during the process i get many messages like

  Past duration 0.994987 too large
  
  Past duration 0.998329 too large
  
  Past duration 0.995995 too large
  
  Past duration 0.997993 too large
  
  Past duration 0.998665 too large
  
  Past duration 0.999321 too large

  also the output file are not printing the "teste" drawtext filter...

  does anyone know what is the problem ?

  how can a really force ffmpeg to split 10 seconds segment (i can accept 9 or 8 seconds segments as an "error margin" but get 13 seconds segments asking for 10 is something really wrong to me)

• Real Time Audio and Video Streaming in C#

  16 novembre 2014, par Nuwan

  I am developing an application which can be used to stream audio and video in real time.
  I can stream in two different ways. I used a capture card to capture live HD stream and
  re send it. And also I need to stream local video file in real time.

  Now I capture video using OpenCV and store frames as bitmaps in blokingCollection bitmap queue.
  After that I encode video frames using ffmpeg (used c# library Nreco) and stored in a queue. Then I send that encoded data through UDP (did not used RTP/RTSP) to omxplayer in raspberry pi and it works very fine.

  Then I captured audio data using ffmpeg
  I used this command to capture and encode audio data.

                   data = ms.ToArray();
  
                   ffMpegTask = ffmpegConverter.ConvertLiveMedia(
  
                          fileName,
  
                          null,
  
                          ms,
  
                          Format.avi,
  
                          new ConvertSettings()
  
                          {                                
  
                              CustomOutputArgs = " -tune zerolatency -ss " + second + " -t " + endTime + " -strict experimental -acodec aac -ab 160k -ac 2 -ar 44100 -vn ",                             
  
                          });
  
                  ffMpegTask.Start();
  
                  ffMpegTask.Stop();
  
                  byte[] data = ms.ToArray();

  After that I saved every audio data packet to queue.

  And I tried to stream these separate audio and video data to omxplayer by using two different
  ports. and received streams by using two omxplayers. And it works fine.

  But what I need to do is multiplex this audio and video stream and send as one stream.
  what I do is first stream two streams as UDP://224.1.1.1:1250(video) and UDP://224.1.1.1:1260(audio)
  then I used nreco invoke method. We can use it to execute ffmpeg commands.

  " -re -i udp://224.1.1.1:1250 -i udp://224.1.1.1:1260 -c copy -f avi udp://224.1.1.1:1270"

  and this works for both audio and video stream but completely out of sync.

  Next thing what I do is creating another ffmpeg ConvertLiveMedia task and write audio and video data
  to that task using write method. And I stream that mux data and received using ffplay. And it plays the stream
  and the sync problem is solved. But sometimes audio and video frames are dropping and then it begins to
  play out of sync.

                  combine = new MemoryStream();
  
                  ffMpegTaskcom = ffmpegConvertercom.ConvertLiveMedia(
  
                          Format.mpeg,
  
                          combine,
  
                          Format.avi,
  
                          new ConvertSettings()
  
                          {
  
                              CustomInputArgs = " ", // windows bitmap pixel format
  
                              CustomOutputArgs = " -threads 7 -c:v libx264 -preset ultrafast -tune zerolatency -strict experimental -profile:v baseline -movflags +faststart -tune film -level 3.0 -tune zerolatency -tune film -pix_fmt yuv420p -g 250 -crf 22 -b:v 4000k -minrate 3000k -maxrate 5000k -acodec aac -ab 160k -ac 2 -ar 44100",
  
  
  
                          });
  
                  ffMpegTaskcom.Start();
  
                  byte[] streamBytesvi = null;
  
                  byte[] streamBytesau = null;
  
                  encodeQueqe.TryDequeue(out streamBytesvi);
  
                  encodeQueqeau.TryDequeue(out streamBytesau);
  
                  ffMpegTaskcom.Write(streamBytesvi, 0, streamBytesvi.Length);
  
                  ffMpegTaskcom.Write(streamBytesau, 0, streamBytesau.Length);
  
  
  
                  //ffMpegTaskcom.Wait();
  
                  ffMpegTaskcom.Stop();

  Now I need to know a good method to deliver audio and video data with synchronization.
  Please tell me what is the wrong I have done or suggest a better way to do this.

  Thank You !

• avcodec/cbs_av1 : fix decoder/encoder_buffer_delay variable types

  4 novembre 2018, par James Almer

  avcodec/cbs_av1 : fix decoder/encoder_buffer_delay variable types
  buffer_delay_length_minus_1 is five bits long, meaning decode_buffer_delay and
  
  encoder_buffer_delay can have values up to 32 bits long.
  Reviewed-by : Mark Thompson <sw@jkqxz.net>
  
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/cbs_av1.h