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• Android App : Convert 3gp to mp3

  18 mars 2013, par user2043332

  My soundfiles should be changed from 3gp to mp3.

  I've tried to do this with ffmpeg :

  ffmpeg -i input.3gp -vn -acodec libmp3lame -ab 64k output.mp3

  But the new mp3 file is only 0 KB big.

  Could libmp3lame be the problem ?
  Is it even possible to do that in Java ?(since I only found c++ examples)

• Android to ffmpeg preview frame is grayscale [closed]

  12 mai 2013, par Estevex

  Hi im using android and ffmpeg together to stream to a Wowza Server. In the android part, I have only this :

  public synchronized void onPreviewFrame(byte[] data, Camera camera) {
  
  /* get video data */
  
  naStream(data); // native method
  
  }

  And on native side using ffmpeg (frame_video is the byte array from android) :

      av_init_packet(&pkt);
  
      avpicture_fill((AVPicture *)picture,frame_video,PIX_FMT_YUV420P,640,480);
  
  
  
          if(ret == 0)
  
              LOGI(7,"avpicture_fill -> error %d", ret);
  
  
  
          /* encode the image */
  
          pkt.data = NULL;
  
          pkt.size = 0;
  
  
  
          ret = avcodec_encode_video2(video_c, &pkt, picture, &got_packet);
  
  
  
          if(ret != 0)
  
              LOGI(7,"avcodec_encode_video2 -> error %d", ret);
  
  
  
          /* if zero size, it means the image was buffered */
  
          if (got_packet) {
  
              if (pkt.pts != AV_NOPTS_VALUE) {
  
                  pkt.pts = av_rescale_q(picture->pts, video_c->time_base, AV_TIME_BASE_Q);
  
              }
  
              if (pkt.dts != AV_NOPTS_VALUE) {
  
                  pkt.dts = av_rescale_q(pkt.dts, video_c->time_base, AV_TIME_BASE_Q);
  
              }
  
  
  
              pkt.duration = av_rescale_q(video_st->duration, video_c->time_base, video_st->time_base);
  
  
  
              if (video_c->coded_frame->key_frame)
  
                  pkt.flags |= AV_PKT_FLAG_KEY;
  
  
  
              /* write the compressed frame in the media file */
  
              ret = av_interleaved_write_frame(oc, &pkt);

  The issue in here is that the stream arrives in a grayscale...
  I tried to convert from NV21 to YUV420P using :

  img_convert_ctx = sws_getContext(video_c->width, video_c->height,PIX_FMT_NV21, video_c->width, video_c->height,PIX_FMT_YUV420P,SWS_FAST_BILINEAR | SWS_PRINT_INFO, NULL, NULL, NULL);
  
  
  
  sws_scale(img_convert_ctx, (const uint8_t * const*)picture->data, picture->linesize, 0,video_c->height, tmp_picture->data, tmp_picture->linesize);
  
  
  
  sws_freeContext(img_convert_ctx);

  But then i cannot write_interleaved packets...

  Im doing the "picture" and "tmp_picture" allocations like this :

  picture = avcodec_alloc_frame();
  
  tmp_picture = avcodec_alloc_frame();
  
  
  
  numBytes=avpicture_get_size(PIX_FMT_YUV420P, video_c->width, video_c->height);
  
  buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
  avpicture_fill((AVPicture *)tmp_picture, buffer, PIX_FMT_YUV420P,video_c->width, video_c->height);

  ---

  After i delete the following lines :

  if (pkt.pts != AV_NOPTS_VALUE) {
  
                  pkt.pts = av_rescale_q(picture->pts, video_c->time_base, AV_TIME_BASE_Q);
  
              }
  
              if (pkt.dts != AV_NOPTS_VALUE) {
  
                  pkt.dts = av_rescale_q(pkt.dts, video_c->time_base, AV_TIME_BASE_Q);
  
              }

  And added :

  if (video_c->coded_frame->pts != AV_NOPTS_VALUE)
  
    pkt.pts = av_rescale_q(video_c->coded_frame->pts,video_c->time_base, video_st->time_base);

  It started writing the interleaved packets but in wowza i cannot see any thing...
  Can anyone help me with this ?

• Cutting video with FFmpeg on Android fails

  21 mars 2013, par Alexey Troshin

  I compiled FFmpeg for Android. Trying to cut the video using command line (as it's realized here).

  The arguments are :

  ffmpeg -i /sdcard/DCIM/Camera/video.mp4 -ss 0 -t 30 -vcodec copy -acodec copy /mnt/sdcard/DCIM/Camera/cut.mp4".

  See this error :

  03-21 16:10:33.616: E/Videokit(16707): /mnt/sdcard/DCIM/Camera/video.mp4: Invalid data found when processing input. 

  What is the problem ?