Newest 'ffmpeg' Questions - Stack Overflow

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• How to run multiple ffmpeg command in using && or |

  31 janvier 2019, par YadavK

  I have create an repeated audio track and then merge it with video. so I have used && operator for that but it gives me and error sample command is like "-stream_loop 2 -i /storage/emulated/0/Movies/Hard.mp3 -c copy -y /storage/emulated/0/Movies/sfsdf.mp3 && -i /storage/emulated/0/Movies/Vid.mp4 -i /storage/emulated/0/Movies/sfsdf.mp3 -map 0v0 -map 1a0 -y -acodec copy -vcodec copy -preset ultrafast -async 1 /storage/emulated/0/Movies/audio_loop.mp4"

  the commands are seperated by && both the commands run well individually but using && operator it will not work. Does anybody having idea about it?

  refernece link : Run ffmpeg multiple commands

  Thanks in advance

• Is there a way to pipe input video into ffmpeg ?

  31 janvier 2019, par Joe Williams

  ffmpeg -f avfoundation -i "1:0" -vf "crop=1920:1080:0:0" -pix_fmt yuv420p -y -r 30 -c:a aac -b:a 128k -f flv rtmp://RTMP_SERVER:RTMP_PORT/STREAM_KEY

  Hello guys, the above command works pretty well. It records the audio/video of the computer. But what I want to do is pipe a repeating video or image(png/jpeg/gif), so that there is no live video feed from the computer, but just the image on the stream with the audio.

  How would you go about doing this?

  Also, if you know any programming interfaces that can do this same thing, please give suggestions. Because I would rather not use a CLI.

• How to fix ffmpeg's offical tutorials03 bug that sound does't work well ?

  31 janvier 2019, par xiaodai

  I want to learn to make a player with ffmpeg and sdl. The tutorial I used is this.[http://dranger.com/ffmpeg/tutorial03.html] Though I have resampled the audio from decode stream, the sound still plays with loud noise.

  I have no ideas to fix it anymore.

  I used the following:

  • the latest ffmpeg and sdl1
  • Visual Studio 2010

  // tutorial03.c
  // A pedagogical video player that will stream through every video frame as fast as it can
  // and play audio (out of sync).
  //
  // This tutorial was written by Stephen Dranger (dranger@gmail.com).
  //
  // Code based on FFplay, Copyright (c) 2003 Fabrice Bellard,
  // and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)
  // Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1
  //
  // Use the Makefile to build all examples.
  //
  // Run using
  // tutorial03 myvideofile.mpg
  //
  // to play the stream on your screen.
  
  extern "C"{
  #include avcodec.h>
  #include avformat.h>
  #include swscale.h>
  #include channel_layout.h>
  #include common.h>
  #include frame.h>
  #include samplefmt.h>
  #include "libswresample/swresample.h"
  
  #include SDL.h>
  #include SDL_thread.h>
  };
  #ifdef __WIN32__
  #undef main /* Prevents SDL from overriding main() */
  #endif
  
  #include 
  
  #define SDL_AUDIO_BUFFER_SIZE 1024
  #define MAX_AUDIO_FRAME_SIZE 192000
  
  struct SwrContext *audio_swrCtx;
  FILE *pFile=fopen("output.pcm", "wb");
  FILE *pFile_stream=fopen("output_stream.pcm","wb");
  int audio_len;
  typedef struct PacketQueue {
      AVPacketList *first_pkt, *last_pkt;
      int nb_packets;
      int size;
      SDL_mutex *mutex;
      SDL_cond *cond;
  } PacketQueue;
  
  PacketQueue audioq;
  
  int quit = 0;
  
  void packet_queue_init(PacketQueue *q) {
      memset(q, 0, sizeof(PacketQueue));
      q->mutex = SDL_CreateMutex();
      q->cond = SDL_CreateCond();
  }
  
  int packet_queue_put(PacketQueue *q, AVPacket *pkt) {
  
      AVPacketList *pkt1;
  
      if(av_dup_packet(pkt) < 0) {
          return -1;
      }
  
      pkt1 = (AVPacketList *)av_malloc(sizeof(AVPacketList));
  
      if(!pkt1) {
          return -1;
      }
  
      pkt1->pkt = *pkt;
      pkt1->next = NULL;
  
  
      SDL_LockMutex(q->mutex);
  
      if(!q->last_pkt) {
          q->first_pkt = pkt1;
      }
  
      else {
          q->last_pkt->next = pkt1;
      }
  
      q->last_pkt = pkt1;
      q->nb_packets++;
      q->size += pkt1->pkt.size;
      SDL_CondSignal(q->cond);
  
      SDL_UnlockMutex(q->mutex);
      return 0;
  }
  
  static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {
      AVPacketList *pkt1;
      int ret;
  
      SDL_LockMutex(q->mutex);
  
      for(;;) {
  
          if(quit) {
              ret = -1;
              break;
          }
  
          pkt1 = q->first_pkt;
  
          if(pkt1) {
              q->first_pkt = pkt1->next;
  
              if(!q->first_pkt) {
                  q->last_pkt = NULL;
              }
  
              q->nb_packets--;
              q->size -= pkt1->pkt.size;
              *pkt = pkt1->pkt;
              av_free(pkt1);
              ret = 1;
              break;
  
          } else if(!block) {
              ret = 0;
              break;
  
          } else {
              SDL_CondWait(q->cond, q->mutex);
          }
      }
  
      SDL_UnlockMutex(q->mutex);
      return ret;
  }
  
   int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size) {
  
  
       static AVPacket pkt; 
       static uint8_t *audio_pkt_data = NULL;
       static int audio_pkt_size = 0;
       static AVFrame frame;
  
       int len1, data_size = 0;
  
       for(;;) {
           while(audio_pkt_size > 0) {
               int got_frame = 0;
               len1 = avcodec_decode_audio4(aCodecCtx, &frame, &got_frame, &pkt);
  
               if(len1 < 0) {
                   /* if error, skip frame */
                   audio_pkt_size = 0;
                   break;
               }
               audio_pkt_data += len1;
               audio_pkt_size -= len1;
               data_size = 0;
               /*
  
               au_convert_ctx = swr_alloc();
               au_convert_ctx=swr_alloc_set_opts(au_convert_ctx,out_channel_layout, out_sample_fmt, out_sample_rate,
               in_channel_layout,pCodecCtx->sample_fmt , pCodecCtx->sample_rate,0, NULL);
               swr_init(au_convert_ctx);
  
               swr_convert(au_convert_ctx,&out_buffer, MAX_AUDIO_FRAME_SIZE,(const uint8_t **)pFrame->data , pFrame->nb_samples);
  
  
               */
               if( got_frame ) {
                   audio_swrCtx=swr_alloc();
                   audio_swrCtx=swr_alloc_set_opts(audio_swrCtx,  // we're allocating a new context
                       AV_CH_LAYOUT_STEREO,//AV_CH_LAYOUT_STEREO,     // out_ch_layout
                       AV_SAMPLE_FMT_S16,         // out_sample_fmt
                       44100, // out_sample_rate
                       aCodecCtx->channel_layout, // in_ch_layout
                       aCodecCtx->sample_fmt,     // in_sample_fmt
                       aCodecCtx->sample_rate,    // in_sample_rate
                       0,                         // log_offset
                       NULL);                     // log_ctx
                   int ret=swr_init(audio_swrCtx);
                   int out_samples = av_rescale_rnd(swr_get_delay(audio_swrCtx, aCodecCtx->sample_rate) + 1024, 44100, aCodecCtx->sample_rate, AV_ROUND_UP);
                   ret=swr_convert(audio_swrCtx,&audio_buf, MAX_AUDIO_FRAME_SIZE,(const uint8_t **)frame.data ,frame.nb_samples);
                   data_size =
                       av_samples_get_buffer_size
                       (
                       &data_size,
                       av_get_channel_layout_nb_channels(AV_CH_LAYOUT_STEREO),
                       ret,
                       AV_SAMPLE_FMT_S16,
                       1
                       );
                    fwrite(audio_buf, 1, data_size, pFile);
                   //memcpy(audio_buf, frame.data[0], data_size);
                   swr_free(&audio_swrCtx);
               }
  
               if(data_size <= 0) {
                   /* No data yet, get more frames */
                   continue;
               }
  
               /* We have data, return it and come back for more later */
               return data_size;
           }
  
           if(pkt.data) {
               av_free_packet(&pkt);
           }
  
           if(quit) {
               return -1;
           }
  
           if(packet_queue_get(&audioq, &pkt, 1) < 0) {
               return -1;
           }
  
           audio_pkt_data = pkt.data;
           audio_pkt_size = pkt.size;
       }
   }
  
  
  
  void audio_callback(void *userdata, Uint8 *stream, int len) {
  
      AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;
      int /*audio_len,*/ audio_size;
  
      static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];
      static unsigned int audio_buf_size = 0;
      static unsigned int audio_buf_index = 0;
  
      //SDL_memset(stream, 0, len);
      while(len > 0) {
  
          if(audio_buf_index >= audio_buf_size) {
              /* We have already sent all our data; get more */
              audio_size = audio_decode_frame(aCodecCtx, audio_buf, audio_buf_size);
  
              if(audio_size < 0) {
                  /* If error, output silence */
                  audio_buf_size = 1024; // arbitrary?
                  memset(audio_buf, 0, audio_buf_size);
  
              } else {
                  audio_buf_size = audio_size;
              }
  
              audio_buf_index = 0;
          }
  
          audio_len = audio_buf_size - audio_buf_index;
  
          if(audio_len > len) {
              audio_len = len;
          }
  
          memcpy(stream, (uint8_t *)audio_buf , audio_len);
          //SDL_MixAudio(stream,(uint8_t*)audio_buf,audio_len,SDL_MIX_MAXVOLUME);
          fwrite(audio_buf, 1, audio_len, pFile_stream);
          len -= audio_len;
          stream += audio_len;
          audio_buf_index += audio_len;
          audio_len=len;
      }
  }
  
  int main(int argc, char *argv[]) {
      AVFormatContext *pFormatCtx = NULL;
      int             i, videoStream, audioStream;
      AVCodecContext  *pCodecCtx = NULL;
      AVCodec         *pCodec = NULL;
      AVFrame         *pFrame = NULL;
      AVPacket        packet;
      int             frameFinished;
  
      //float           aspect_ratio;
  
      AVCodecContext  *aCodecCtx = NULL;
      AVCodec         *aCodec = NULL;
  
      SDL_Overlay     *bmp = NULL;
      SDL_Surface     *screen = NULL;
      SDL_Rect        rect;
      SDL_Event       event;
      SDL_AudioSpec   wanted_spec, spec;
  
      struct SwsContext   *sws_ctx            = NULL;
      AVDictionary        *videoOptionsDict   = NULL;
      AVDictionary        *audioOptionsDict   = NULL;
  
      if(argc < 2) {
              fprintf(stderr, "Usage: test \n");
              exit(1);
          }
  
          // Register all formats and codecs
      av_register_all();
  
      if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
          fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
          exit(1);
      }
  
      // Open video file
      if(avformat_open_input(&pFormatCtx, argv[1]/*"file.mov"*/, NULL, NULL) != 0) {
          return -1;    // Couldn't open file
      }
  
      // Retrieve stream information
      if(avformat_find_stream_info(pFormatCtx, NULL) < 0) {
          return -1;    // Couldn't find stream information
      }
  
      // Dump information about file onto standard error
      av_dump_format(pFormatCtx, 0, argv[1], 0);
  
      // Find the first video stream
      videoStream = -1;
      audioStream = -1;
  
      for(i = 0; i < pFormatCtx->nb_streams; i++) {
          if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
              videoStream < 0) {
                  videoStream = i;
          }
  
          if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO &&
              audioStream < 0) {
                  audioStream = i;
          }
      }
  
      if(videoStream == -1) {
          return -1;    // Didn't find a video stream
      }
  
      if(audioStream == -1) {
          return -1;
      }
  
      aCodecCtx = pFormatCtx->streams[audioStream]->codec;
      // Set audio settings from codec info
      wanted_spec.freq = 44100;
      wanted_spec.format = AUDIO_S16SYS;
      wanted_spec.channels = av_get_channel_layout_nb_channels(AV_CH_LAYOUT_STEREO);;
      wanted_spec.silence = 0;
      wanted_spec.samples = 1024;
      wanted_spec.callback = audio_callback;
      wanted_spec.userdata = aCodecCtx;
  
      if(SDL_OpenAudio(&wanted_spec, &spec) < 0) {
          fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
          return -1;
      }
  
  
      aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
  
      if(!aCodec) {
          fprintf(stderr, "Unsupported codec!\n");
          return -1;
      }
  
      avcodec_open2(aCodecCtx, aCodec, &audioOptionsDict);
  
      // audio_st = pFormatCtx->streams[index]
      packet_queue_init(&audioq);
      SDL_PauseAudio(0);
  
      // Get a pointer to the codec context for the video stream
      pCodecCtx = pFormatCtx->streams[videoStream]->codec;
  
      // Find the decoder for the video stream
      pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
      if(pCodec == NULL) {
          fprintf(stderr, "Unsupported codec!\n");
          return -1; // Codec not found
      }
  
      // Open codec
      if(avcodec_open2(pCodecCtx, pCodec, &videoOptionsDict) < 0) {
          return -1;    // Could not open codec
      }
  
      // Allocate video frame
      pFrame = av_frame_alloc();
  
      // Make a screen to put our video
  
  #ifndef __DARWIN__
      screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
  #else
      screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);
  #endif
  
      if(!screen) {
          fprintf(stderr, "SDL: could not set video mode - exiting\n");
          exit(1);
      }
  
      // Allocate a place to put our YUV image on that screen
      bmp = SDL_CreateYUVOverlay(pCodecCtx->width,
          pCodecCtx->height,
          SDL_YV12_OVERLAY,
          screen);
      sws_ctx =
          sws_getContext
          (
          pCodecCtx->width,
          pCodecCtx->height,
          pCodecCtx->pix_fmt,
          pCodecCtx->width,
          pCodecCtx->height,
          PIX_FMT_YUV420P,
          SWS_BILINEAR,
          NULL,
          NULL,
          NULL
          );
  
  
      // Read frames and save first five frames to disk
      i = 0;
  
      while(av_read_frame(pFormatCtx, &packet) >= 0) {
          // Is this a packet from the video stream?
          if(packet.stream_index == videoStream) {
              // Decode video frame
              avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished,
                  &packet);
  
              // Did we get a video frame?
              if(frameFinished) {
                  SDL_LockYUVOverlay(bmp);
  
                  AVPicture pict;
                  pict.data[0] = bmp->pixels[0];
                  pict.data[1] = bmp->pixels[2];
                  pict.data[2] = bmp->pixels[1];
  
                  pict.linesize[0] = bmp->pitches[0];
                  pict.linesize[1] = bmp->pitches[2];
                  pict.linesize[2] = bmp->pitches[1];
  
                  // Convert the image into YUV format that SDL uses
                  sws_scale
                      (
                      sws_ctx,
                      (uint8_t const * const *)pFrame->data,
                      pFrame->linesize,
                      0,
                      pCodecCtx->height,
                      pict.data,
                      pict.linesize
                      );
  
                  SDL_UnlockYUVOverlay(bmp);
  
                  rect.x = 0;
                  rect.y = 0;
                  rect.w = pCodecCtx->width;
                  rect.h = pCodecCtx->height;
                  SDL_DisplayYUVOverlay(bmp, &rect);
                  SDL_Delay(40);
                  av_free_packet(&packet);
              }
  
          } else if(packet.stream_index == audioStream) {
              packet_queue_put(&audioq, &packet);
  
          } else {
              av_free_packet(&packet);
          }
  
          // Free the packet that was allocated by av_read_frame
          SDL_PollEvent(&event);
  
          switch(event.type) {
          case SDL_QUIT:
              quit = 1;
              SDL_Quit();
              exit(0);
              break;
  
          default:
              break;
          }
  
      }
  
      // Free the YUV frame
      av_free(pFrame);
      /*swr_free(&audio_swrCtx);*/
      // Close the codec
      avcodec_close(pCodecCtx);
      fclose(pFile);
      fclose(pFile_stream);
      // Close the video file
      avformat_close_input(&pFormatCtx);
  
      return 0;
  }
  

  I hope to play normally.

• Can I dynamic crop two input video then stack them using ffmpeg ?

  31 janvier 2019, par Wei Deng

  I want to make an effect of switching back and forth between two videos.

  I tried to dynamic crop two input video then stack them using ffmpeg:

  ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex \
  "[0:v]crop=iw:'2+(mod(n,ih))':0:0[a];[1:v]crop=iw:'ih-2- 
  (mod(n,ih))':0:'2+(mod(n,ih))'[b];[a][b]vstack=inputs=2[v]" \
  -map [v] output.mp4
  

  Skip 2 pixel to prevent crop zero.

  But the output video is not what I want. It seems '(mod(n,ih))' is zero all the time.

  I don't know what's wrong with it.

• React Native + FFProbe + FFMpeg

  31 janvier 2019, par Adam Soffer

  Is it possible to use FFmpeg or FFprobe inside a react native app for interacting with a video stream? I see an FFprobe package published to npm but it's only Node.js compatible: https://www.npmjs.com/package/ffprobe