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• ffmpeg and hardcoding subtitles

  8 avril 2015, par Adin Gill

  I have a command like so

  ffmpeg -i "F:\Filebotted\Rail Wars\Season 1\Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv" -map 0:0 -map 0:1 -b:v 750k -b:a 128k -c:v libx264 -c:a mp3 -ac 2 -filter_complex "subtitles=F:\Filebotted\Rail Wars\Season 1\Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv,scale=-1:360" "C:\Users\Adin\Desktop\Testy mc test\Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv"

  Yes it is long but unfortunatly ffmpeg chucks a hissy fit and spits out the following

  [subtitles @ 00000000050ce7c0] Unable to parse option value "FilebottedRail Wars
  
  Season 1Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv" as image size
  
      Last message repeated 1 times
  
  [subtitles @ 00000000050ce7c0] Error setting option original_size to value Fileb
  
  ottedRail WarsSeason 1Rail Wars.S01E07(7).You Look Good in That. 1080p.mkv.
  
  [Parsed_subtitles_0 @ 0000000002c714c0] Error applying options to the filter.
  
  [AVFilterGraph @ 0000000002c5c540] Error initializing filter 'subtitles' with ar
  
  gs 'F:FilebottedRail WarsSeason 1Rail Wars.S01E07(7).You Look Good in That. 1080
  
  p.mkv'
  
  Error configuring filters.

  It works just fine when the file is in the same folder as ffmpeg (I found out that it doesn’t like ’ or - in the filename, but I just spent an hour trying to work out the issue with no avail.

  Any help will be appreciated :)

• AV playback synchronization using ffmpeg on WPF

  10 août 2017, par learner

  I have Video( H264-1080p-30fps) and Audio (Mu-law-8k) in separate files both are generated from same camera source. My work is to play them both synchronously using ffmpeg. I can able to decode video and audio without any issue but I don’t know how to play AV synchronously on WPF.

  1. What is the best way to render the video and play audio on Wpf after decoding ?
  2. How to play them synchronously ?

  Thanks in advance..

• Resize camera preview frame using Ffmpeg

  20 avril 2015, par Vipul Purohit

  Scenario :
  I’m working on a live video stream application, in that I need to stream video at resolution around 380x240. I’m sending the camera preview byte[] to streamer from onPreviewFrame event of Camera.PreviewCallback.
  But I need to show camera preview in 720p/1080p but its not possible due to low resolution video streaming.

  Problem
  The solution I’m working is to reduce the video frame size from HD to a low resolution and then send it to streamer and for that I’m using FFMPEG’s sws_scale.

  I’ve successfully compiled the FFMPEG and can access and execute the JNI methods. But I’m completely new to android NDK development and not very familiar with the C/C++ language so I need help in writing JNI method to scale down the video frame.

  Here is what I’m having in my JNI method :

  JNIEXPORT jbyteArray JNICALL Java_com_example_ffmpegtest_MainActivity_resizeFrame(
  
      JNIEnv * env, jobject pObj, jbyteArray *input, jbyteArray * output,
  
      int width, int height) {
  
  struct SwsContext *resize;
  
  
  
  resize = sws_getContext(width, height, PIX_FMT_YUV420P, width, height,
  
          AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
  
  LOGI("---RESIZE");
  
  AVFrame* picture = avcodec_alloc_frame(); // this is your original frame
  
  AVFrame* outpic = avcodec_alloc_frame();
  
  
  
  int num_bytes = avpicture_get_size(PIX_FMT_YUV420P, width, height);
  
  jbyteArray data = (*env)->NewByteArray(env, num_bytes);
  
  uint8_t* frame2_buffer = (uint8_t *) av_malloc(num_bytes * sizeof(uint8_t));
  
  LOGI("---NUMBYTES ED");
  
  
  
  avpicture_fill((AVPicture*) picture, input, PIX_FMT_YUV420P, width, width);
  
  
  
  avpicture_fill((AVPicture*) outpic, frame2_buffer, PIX_FMT_YUV420P, 600,
  
          600);
  
  
  
  sws_scale(resize, picture->data, picture->linesize, 600, 600, outpic->data,
  
          outpic->linesize);
  
  
  
  sws_freeContext(resize);
  
  
  
  (*env)->SetByteArrayRegion(env, data, 0, num_bytes, outpic);
  
  LOGI("---SCALE %d", picture->data);
  
  LOGI("---SCALE_OUT %d", outpic->data);
  
  return output;

  }

  Here is the fuction for JNI method :

  private static native byte[] resizeFrame(byte[] input, byte[] output, int width, int height);

  and the Camera.PreviewCallback

  @Override
  
  public void onPreviewFrame(byte[] data, Camera camera) {
  
      byte[] data2 = null;
  
  
  
      data2 = resizeFrame(data, data2, mPreview.mPreviewSize.width,
  
              mPreview.mPreviewSize.height);
  
  
  
      // Code to send camera frame to streamer
  
  }

  I’m always getting data2 null.
  I know its a bad coding practices but I’m just keep changing the code to make it work but failed.