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• How to reconnect using avformat_open_input without having to alloc the decoder again ?

  26 septembre 2012, par Jona

  Currently, I have a code based on ffplay to stream live content.

  One thing I'm looking to do is be able to reconnect upon loosing a connection without having to shutdown the whole decoding process.

  To me the solution is alloc the decoder myself once and keep using it across reconnections. I can't seem to figure out how to setup a decoder without having to depend on the AVFormatContext. Right now my code is failing when trying to use my own allocated AVCodecContext to decode. But it doesn't fail if I use the AVCodecContext given by AVFormatContext.

  This is part of my initial code :

  // attempt to find more information about the codec
  
  // also it will open the codecs needed.
  
  fferror = avformat_find_stream_info(ic, NULL);
  
  if (0 > fferror)
  
  {
  
      // TODO verify type of error to better map it to our errors
  
      error = ERROR_FAIL_TO_CONNECT;
  
      LOGE("download() -> avformat_find_stream_info failed! fferror:%d, error:%d", fferror, error);
  
      goto fail;
  
  }
  
  
  
  AVCodec *dec;
  
  // select the audio stream
  
  int ret = av_find_best_stream(ic, AVMEDIA_TYPE_AUDIO, -1, -1, &dec, 0);
  
  if (0 > ret) {
  
      error = ERROR_UNEXPECTED_ERROR;
  
      LOGE("download() -> av_find_best_stream failed! ret:%d, error:%d", ret, error);
  
      goto fail;
  
  }
  
  
  
  LOGI("download() -> STREAM: nb_streams:%d", ic->nb_streams);
  
  LOGI("download() -> STREAM: audio format:%s", ic->iformat->name);
  
  LOGI("download() -> STREAM: audio bitrate:%d", ic->bit_rate);
  
  
  
  
  
  // save the audio stream index and source
  
  is->audio_stream_index = ret;
  
  is->audio_st = ic->streams[is->audio_stream_index];
  
  is->audio_buf_size = 0;
  
  is->audio_buf_index = 0;
  
  
  
  is->audio_st->discard = AVDISCARD_DEFAULT;
  
  
  
  if(ic->pb) {
  
      ic->pb->eof_reached= 0; //FIXME hack, ffplay maybe should not use url_feof() to test for the end
  
  }
  
  
  
  if (show_status) {
  
          av_dump_format(ic, 0, is->filename, 0);
  
      }
  
  
  
  // open codec
  
      error = open_decoder(is->audio_st->codec, dec);
  
      if (ERROR_NO_ERROR != error) {
  
          LOGE("receive_thread() -> open_decoder failed! error:%d", error);
  
          goto fail;
  
      }

  And this is the funtion that initializes the decoder.

  static int open_decoder (AVCodecContext *avctx, AVCodec *codec)
  
  {
  
      int fferror         = 0;
  
      AVCodecContext *c   = NULL;
  
  
  
      if (smDecoder.open) {
  
          LOGW("open_decoder() -> decoder is already open!");
  
          return ERROR_NO_ERROR;
  
      }
  
  
  
      // find the decoder
  
      if (!codec)
  
      {
  
          codec = avcodec_find_decoder(avctx->codec_id);
  
          if (!codec)
  
          {
  
              LOGE("open_decoder() -> avcodec_find_decoder failed!");
  
              return ERROR_UNEXPECTED_ERROR;
  
          }
  
      }
  
  
  
      // allocate the decoder av context
  
      c = avcodec_alloc_context3(codec);
  
      if (NULL == c) {
  
          LOGE("open_decoder() -> avcodec_alloc_context3 failed! Out of memory?");
  
          return ERROR_UNEXPECTED_ERROR;
  
      }
  
  
  
      // check if the type of codec we support
  
      if (AVMEDIA_TYPE_AUDIO != c->codec_type)
  
      {
  
          LOGE("open_decoder() -> codec_type not supported! codec_type:%d",c->codec_type);
  
          return ERROR_UNEXPECTED_ERROR;
  
      }
  
  
  
      // set the proper channels if not properly set
  
      if (c->channels > 0) {
  
          c->request_channels = FFMIN(2, c->channels);
  
      } else {
  
          c->request_channels = 2;
  
      }
  
  
  
      c->debug_mv = 0;
  
      c->debug = 0;
  
      c->workaround_bugs = workaround_bugs;
  
      c->idct_algo= idct;
  
      if(fast) c->flags2 |= CODEC_FLAG2_FAST;
  
      c->error_concealment= error_concealment;
  
      c->thread_count = thread_count;
  
  
  
      // open the decoder
  
      fferror = avcodec_open2(avctx, codec, NULL);
  
      if (fferror < 0)
  
      {
  
          LOGE("open_decoder() -> avcodec_open2 failed! fferror:%d", fferror);
  
          return ERROR_UNEXPECTED_ERROR;
  
      }
  
  
  
      // clean up our reusable packet
  
      memset(&smDecoder.audio_pkt, 0, sizeof(smDecoder.audio_pkt));
  
  
  
      smDecoder.open = 1;
  
      smDecoder.codec = codec;
  
      smDecoder.avctx = c;
  
  
  
      return ERROR_NO_ERROR;
  
  }

• "File descriptor in bad state" error while running ffmpeg on android device and selecting an input device

  25 août 2012, par user1545779

  Below is the output of the ffmpeg command :# ./ffmpeg -y -f s16le -i /dev/snd/pcmC3D0c 1640.wmv -to create an audio file from a Logitech webcam on an android device.

  As shown in the output, I received a File descriptor in bad state error for referring to the mic input as /dev/snd/pcmC3D0c I determined the value of the device (webcam mic) by reviewing the contents of /proc/asound. The webcam mic was card3 and its STREAM0 file indicated that the mic has an audio format of format S16_LE

  It was also confirmed that it is a capture device and its' pcm id was pcmC3D0c (C3 being the card number and D0 being the Device number. I then confirmed the correct device by checking the /dev/snd/ directory to confirm its proper and full description. The /dev/snd folder confirmed that the mic was /dev/snd/pcmC3D0c

  I then checked the permissions and ownership to make sure that I could use that device. Hence as far as identifying the correct device to used I do believe that /dev/snd/pcmC3D0c is the correct device. I do believe this error could possibly have something to do with the OS, however after all these checks, I still cannot figure out what is giving the bad file descriptor state error.

  Please note that I tested for different output formats, etc and that did not make any difference. Any leads or suggestions ?

  # ./ffmpeg -y -f s16le -i /dev/snd/pcmC3D0c 1640.wmv

  ffmpeg version N-43170-gd84dd35 Copyright (c) 2000-2012 the FFmpeg developers
  built on Aug 24 2012 09:16:05 with gcc 4.4.3 (GCC) configuration : —enable-cross-compile —arch=arm —cpu=cortex-a9 —target-os=linux —enable-runtime-cpudetect —prefix=/output —enable-pic —cross-prefix=/home/jasongipsyblues/Desktop/apps/android-ndk-r8b/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86/bin/arm-linux-androideabi- —sysroot=/home/jasongipsyblues/Desktop/apps/android-ndk-r8b/platforms/android-14/arch-arm —enable-version3 —enable-gpl —enable-memalign-hack —disable-doc —enable-yasm —enable-libx264 —enable-zlib —extra-cflags=-I../x264 —extra-ldflags='-L../x264 -lc'

  libavutil 51. 66.100 / 51. 66.100
  libavcodec 54. 48.100 / 54. 48.100
  libavformat 54. 22.100 / 54. 22.100
  libavdevice 54. 2.100 / 54. 2.100
  libavfilter 3. 5.102 / 3. 5.102
  libswscale 2. 1.100 / 2. 1.100
  libswresample 0. 15.100 / 0. 15.100
  libpostproc 52. 0.100 / 52. 0.100

  [s16le @ 0xfd84f0] Invalid sample rate 0 specified using default of 44100
  [s16le @ 0xfd84f0] Estimating duration from bitrate, this may be inaccurate
  Guessed Channel Layout for Input Stream #0.0 : mono
  Input #0, s16le, from '/dev/snd/pcmC3D0c' :
  Duration : N/A, bitrate : 705 kb/s
  Stream #0:0 : Audio : pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
  Output #0, asf, to '1640.wmv' :
  Metadata :
  WM/EncodingSettings : Lavf54.22.100
  Stream #0:0 : Audio : wmav2 (a[1][0][0] / 0x0161), 44100 Hz, mono, s16, 128 kb/s
  Stream mapping :
  Stream #0:0 -> #0:0 (pcm_s16le -> wmav2)
  Press [q] to stop, [?] for help
  
  /dev/snd/pcmC3D0c : File descriptor in bad state
  size= 1kB time=00:00:00.00 bitrate= 0.0kbits/s
  video:0kB audio:0kB subtitle:0 global headers:0kB muxing overhead 5340.000000%

• Open stream with FFmpeg libavformat exits with I/O error after once in Android Application

  15 février 2015, par miazima

  I am trying to open a video stream in an android application. The first time I open the stream, the stream is opened and everything runs fine. However, if I press back and open the stream again, the app crashes.

  I am a newbie to this, so I used log statements to see if the argument values for the methods could lead me to the issue. I figured out that avformat_open_input(&ic, is->filename, is->iformat, NULL) is returning I/O error. However I can’t figure out where the error lies, the filename and the format is the same but am not sure about the &ic which is from is->ic = (AVFormatContext*) avformat_alloc_context(), I would appreciate any help !

  void get_video_info(int p_debug, const char* path) {
  
  
  
      int flags;
  
      //VideoState *is;
  
      int err, i, orig_nb_streams, ret;
  
      isquit = 0;
  
      av_log_set_flags(AV_LOG_SKIP_REPEATED);
  
      int st_index[3];
  
      st_index[AVMEDIA_TYPE_AUDIO]=-1;
  
      st_index[AVMEDIA_TYPE_VIDEO]=-1;
  
      /* register all codecs, demux and protocols */
  
      avcodec_register_all();
  
  #if CONFIG_AVDEVICE
  
      avdevice_register_all();
  
  #endif
  
  #if CONFIG_AVFILTER
  
      avfilter_register_all();
  
  #endif
  
      av_register_all();
  
  #if CONFIG_NETWORK
  
      ret = avformat_network_init();
  
  #endif
  
       if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
  
              fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
  
              exit(1);
  
            }
  
  
  
      av_init_packet(&flush_pkt);
  
      flush_pkt.data = "FLUSH";
  
  
  
      // open video stream
  
      is = av_mallocz(sizeof(VideoState));
  
      if (!is) {
  
          do_exit(NULL);
  
          return;
  
      }
  
  
  
      is->abort_request = 0; // FIXME: abort_request changes when on closing or exit
  
      is->pictq_mutex = SDL_CreateMutex();
  
      is->pictq_cond = SDL_CreateCond();
  
      is->pictq_size = 0;
  
      is->pictq_rindex = 0;
  
      is->pictq_windex = 0;
  
      is->av_sync_type = av_sync_type;//AV_SYNC_AUDIO_MASTER;//
  
  
  
      if(path != NULL)
  
      {
  
          av_strlcpy(is->filename, path, sizeof(is->filename));
  
      }
  
      else
  
      {
  
          if(streamProtocal==0) {
  
              av_strlcpy(is->filename, "/sdcard/download/sdp_file.sdp", sizeof(is->filename));
  
          }
  
          else
  
          {
  
              av_strlcpy(is->filename, "udp://@:3001", sizeof(is->filename));
  
              is->iformat = av_find_input_format("m4v");
  
          }
  
      }
  
      is->ic = (AVFormatContext*) avformat_alloc_context();
  
      //It is assumed that server always sends m4v data, so that codec search can be avoided
  
      AVFormatContext *ic = is->ic;
  
  
  
      if ((err = avformat_open_input(&ic, is->filename, is->iformat, NULL))
  
              != 0) {
  
          LOGE(1, "Error open video file: %s", is->filename);
  
          char* error = (char*)malloc(1024);
  
          av_strerror(err, error, 1024);
  
          LOGE(1, "Error open video file: %s", error);
  
          do_exit(is);
  
      }
  
      LOGE(1, "entered get_video_info");
  
      is->ic = ic;
  
  
  
      orig_nb_streams = ic->nb_streams;
  
      if ((err = avformat_find_stream_info(is->ic, NULL)) < 0) {
  
          LOGE(1, "Error find stream information: %d", err);
  
          return;
  
      }
  
      LOGE(1, "avformat_find_stream_info");
  
      if(is->ic->pb)
  
          is->ic->pb->eof_reached= 0;//FIXME hack, ffplay maybe should not use url_feof() to test for the end
  
      AVCodec *lvideoCodec;
  
  
  
  int g_audio_file_type = 0;
  
      // Find the first video stream
  
          for (i=0; iic->nb_streams; i++) {
  
              //take video stream only for video file types
  
              if (g_audio_file_type == 0)  {
  
                  if (is->ic->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO &&
  
                          st_index[AVMEDIA_TYPE_VIDEO] < 0)
  
                  {
  
                      st_index[AVMEDIA_TYPE_VIDEO]=i;
  
                  }
  
              }
  
  
  
              if(is->ic->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO &&
  
                      st_index[AVMEDIA_TYPE_AUDIO] < 0)
  
              {
  
                  st_index[AVMEDIA_TYPE_AUDIO]=i;
  
              }
  
  
  
          }
  
      if (st_index[AVMEDIA_TYPE_AUDIO] >= 0) {
  
          stream_component_open(is, st_index[AVMEDIA_TYPE_AUDIO]);
  
      }
  
      if (st_index[AVMEDIA_TYPE_VIDEO] >= 0) {
  
          stream_component_open(is, st_index[AVMEDIA_TYPE_VIDEO]);
  
      }
  
      if (is->video_stream < 0) {
  
          do_exit(is);
  
          return;
  
      }
  
      is->read_tid = SDL_CreateThread(read_thread, is);
  
      rgb_frame = avcodec_alloc_frame();
  
  }