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• ffmpeg got black and white video when encoding flv

  17 décembre 2012, par samyou

  i searched the site and got a post :
  getting black and white image after encoding
  but i got no answer.

  don't know how but it is all black and white.

  hear is the init code :

  JNIEXPORT jboolean JNICALL Java_sam_flvmuxer_SamRTMPNative_nativeInitMuxerAndStart(
  
      JNIEnv *env, jclass jcls, jstring outfile, jint inwidth, jint inheight,
  
      jint fps) {
  
  audioOutBuffer = malloc(AUDIO_OUT_BUFFER_SIZE);
  
  videoOutBuffer = malloc(VIDEO_OUT_BUFFER_SIZE);
  
  VIDEO_WIDTH = inwidth;
  
  VIDEO_HEIGHT = inheight;
  
  av_log_set_callback(samffmpeglogback);
  
  av_register_all();
  
  char *filepath = (*env)->GetStringUTFChars(env, outfile, 0);
  
  JNILOG("file path is %s",filepath);
  
  avformat_alloc_output_context2(&avFormatContext, NULL, NULL, filepath);
  
  if (!avFormatContext) {
  
      JNILOG("avformat_alloc_output_context2 with filepath failed");
  
      return JNI_FALSE;
  
  }
  
  AVOutputFormat *fmt = avFormatContext->oformat;
  
  //fmt->video_codec = VIDEO_CODEC_ID;
  
  ////init video
  
  avVideoStream = avformat_new_stream(avFormatContext, NULL );
  
  if (!avVideoStream) {
  
      (*env)->ReleaseStringUTFChars(env, outfile, filepath);
  
      return 0;
  
  }
  
  
  
  AVCodec *videocodec = avcodec_find_encoder(VIDEO_CODEC_ID);
  
  if (!videocodec) {
  
      JNILOG("avcodec_find_encoder error");
  
      return JNI_FALSE;
  
  }
  
  avcodec_get_context_defaults3(avVideoStream->codec, videocodec);
  
  
  
  AVCodecContext *avVideoCodecContext = avVideoStream->codec;
  
  avVideoCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
  
  avVideoCodecContext->codec_id = VIDEO_CODEC_ID;
  
  avVideoCodecContext->width = inwidth;
  
  avVideoCodecContext->height = inheight;
  
  avVideoCodecContext->time_base.den = fps;
  
  avVideoCodecContext->time_base.num = 1;
  
  avVideoCodecContext->gop_size = 10;
  
  avVideoCodecContext->pix_fmt = PIX_FMT_YUV420P;
  
  JNILOG("bitrate befort set = %d",avVideoCodecContext->bit_rate);
  
  avVideoCodecContext->bit_rate = 600000;
  
  
  
  
  
  if (fmt->flags & AVFMT_GLOBALHEADER)
  
      avVideoCodecContext->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
  av_dump_format(avFormatContext,0,filepath,1);
  
  if(avcodec_open2(avVideoCodecContext,videocodec,NULL)<0)
  
  {
  
      JNILOG("video avcodec_open2 failed");
  
      (*env)->ReleaseStringUTFChars(env, outfile, filepath);
  
      return JNI_FALSE;
  
  }
  
  
  
  
  
  
  
  ///////
  
  /* open the output file, if needed */
  
  if (!(fmt->flags & AVFMT_NOFILE)) {
  
      if ((avio_open(&avFormatContext->pb, filepath, AVIO_FLAG_WRITE)) < 0) {
  
          JNILOG("Could not open file!");
  
          (*env)->ReleaseStringUTFChars(env, outfile, filepath);
  
          return 0;
  
      }
  
  }
  
  if (avformat_write_header(avFormatContext, NULL ) < 0) {
  
      JNILOG("Could not avformat_write_header!");
  
      (*env)->ReleaseStringUTFChars(env, outfile, filepath);
  
      return 0;
  
  }
  
  (*env)->ReleaseStringUTFChars(env, outfile, filepath);
  
  YUVFrame = avcodec_alloc_frame();
  
  JNILOG("ffmpeg every thing inited");
  
  return JNI_TRUE;
  
  }

  and encode code looks like below :

  avpicture_fill((AVPicture *)YUVFrame,framedata,PIX_FMT_YUV420P,VIDEO_WIDTH,VIDEO_HEIGHT);
  
      ///打印data 分量!!!!
  
      AVPacket pkt;
  
      av_init_packet(&pkt);
  
      pkt.data = videoOutBuffer;
  
      pkt.size = VIDEO_OUT_BUFFER_SIZE;
  
      int gotpkt = 0;
  
      avcodec_encode_video2(avVideoStream->codec,&pkt,YUVFrame,&gotpkt);
  
      if (gotpkt > 0) {
  
          JNILOG("encoded size=%d,gotpktflag=%d",pkt.size,gotpkt);
  
          pkt.stream_index = avVideoStream->index;
  
          pkt.flags |= AV_PKT_FLAG_KEY;
  
          pkt.pts = timestamp;
  
          while (pkt.pts <= lastVideoPts) {
  
              pkt.pts++;
  
          }
  
          lastVideoPts = pkt.pts;
  
          if (av_interleaved_write_frame(avFormatContext, &pkt) < 0) {
  
              JNILOG("av_interleaved_write_frame failed");
  
          }
  
      }

  someone please help me with this problem^^

• How to Replace Duplicate Frames in a Video with Black Frames using ffmpeg ?

  21 mars 2021, par Yam Shargil

  I'm trying to trim all "no action, no movement" frames out of my screen recording. Some of my screen recordings are really long (like 100 hours long).

  


  I found this :
How to Simply Remove Duplicate Frames from a Video using ffmpeg

  


  ffmpeg -i in.mp4 -vf
"select='if(gt(scene,0.01),st(1,t),lte(t-ld(1),1))',setpts=N/FRAME_RATE/TB"
trimmed.mp4


  


  I don't want to lose any important frames, so for testing the threshold purposes, I want to replace (not remove) all the "no action" frames with black frames.

  


  That's my best shot so far, not my proudest work :

  


  ffmpeg -i in.mp4 -vf "select='if(gt(scene,0.01),st(1,t),lte(t-ld(1),1))',drawbox=color=black:t=fill" out.mp4


  


• Using ffmpeg to overlay black line or add border to two side by side videos

  14 février 2020, par user3135427

  I am using the following to generate a video that is side by side.

  ffmpeg -i left.mp4 -i right.mp4 -filter_complex "[0:v]setpts=PTS-STARTPTS, pad=iw*2:ih[bg]; [1:v]setpts=PTS-STARTPTS[fg]; [bg][fg]overlay=w" -y final.mp4

  It looks like this.

  http://www.mo-de.net/d/partnerAcrobatics.mp4

  I would like to place a vertical black line on top right in the middle or add a black border to the video on the left. If I add a border to the left video I would like to maintain the original sum dimension of the original videos. This solution would require subtracting the border width from the left videos width. I will take either solution.

  Thanks