zoneminder/src/zm_ffmpeg_input.cpp

#include "zm_ffmpeg_input.h"

#include "zm_ffmpeg.h"
#include "zm_logger.h"

FFmpeg_Input::FFmpeg_Input() {
  input_format_context = nullptr;
  video_stream_id = -1;
  audio_stream_id = -1;
  FFMPEGInit();
  streams = nullptr;
  frame = nullptr;
	last_seek_request = -1;
}

FFmpeg_Input::~FFmpeg_Input() {
  if ( input_format_context ) {
    Close();
  }
  if ( frame ) {
    av_frame_free(&frame);
    frame = nullptr;
  }
}  // end ~FFmpeg_Input()

/* Takes streams provided from elsewhere.  They might not come from the same source
 * but we will treat them as if they are.  */
int FFmpeg_Input::Open(
    const AVStream * video_in_stream,
    const AVCodecContext * video_in_ctx,
    const AVStream * audio_in_stream,
    const AVCodecContext * audio_in_ctx
    ) {
  video_stream_id = video_in_stream->index;
  int max_stream_index = video_in_stream->index;

  if ( audio_in_stream ) {
    max_stream_index = video_in_stream->index > audio_in_stream->index ? video_in_stream->index : audio_in_stream->index;
    audio_stream_id = audio_in_stream->index;
  }
  streams = new stream[max_stream_index+1];
  return 1;
}

int FFmpeg_Input::Open(const char *filepath) {

  int error;

  /** Open the input file to read from it. */
  error = avformat_open_input(&input_format_context, filepath, nullptr, nullptr);
  if ( error < 0 ) {
    Error("Could not open input file '%s' (error '%s')",
        filepath, av_make_error_string(error).c_str());
    input_format_context = nullptr;
    return error;
  }

  /** Get information on the input file (number of streams etc.). */
  if ( (error = avformat_find_stream_info(input_format_context, nullptr)) < 0 ) {
    Error(
        "Could not open find stream info (error '%s')",
        av_make_error_string(error).c_str()
        );
    avformat_close_input(&input_format_context);
    return error;
  }

  streams = new stream[input_format_context->nb_streams];
  Debug(2, "Have %d streams", input_format_context->nb_streams);

  for ( unsigned int i = 0; i < input_format_context->nb_streams; i += 1 ) {
    if ( is_video_stream(input_format_context->streams[i]) ) {
      zm_dump_stream_format(input_format_context, i, 0, 0);
      if ( video_stream_id == -1 ) {
        video_stream_id = i;
        // if we break, then we won't find the audio stream
      } else {
        Warning("Have another video stream.");
      }
    } else if ( is_audio_stream(input_format_context->streams[i]) ) {
      if ( audio_stream_id == -1 ) {
        Debug(2, "Audio stream is %d", i);
        audio_stream_id = i;
      } else {
        Warning("Have another audio stream.");
      }
    } else {
      Warning("Unknown stream type");
    }

    streams[i].frame_count = 0;
#if LIBAVCODEC_VERSION_CHECK(57, 64, 0, 64, 0)
    streams[i].context = avcodec_alloc_context3(nullptr);
    avcodec_parameters_to_context(streams[i].context, input_format_context->streams[i]->codecpar);
#else
    streams[i].context = input_format_context->streams[i]->codec;
#endif

    if ( !(streams[i].codec = avcodec_find_decoder(streams[i].context->codec_id)) ) {
      Error("Could not find input codec");
      avformat_close_input(&input_format_context);
      return AVERROR_EXIT;
    } else {
      Debug(1, "Using codec (%s) for stream %d", streams[i].codec->name, i);
    }

    error = avcodec_open2(streams[i].context, streams[i].codec, nullptr);
    if ( error < 0 ) {
      Error("Could not open input codec (error '%s')",
          av_make_error_string(error).c_str());
#if LIBAVCODEC_VERSION_CHECK(57, 64, 0, 64, 0)
      avcodec_free_context(&streams[i].context);
#endif
      avformat_close_input(&input_format_context);
      input_format_context = nullptr;
      return error;
    }
  } // end foreach stream

  if ( video_stream_id == -1 )
    Debug(1, "Unable to locate video stream in %s", filepath);
  if ( audio_stream_id == -1 )
    Debug(3, "Unable to locate audio stream in %s", filepath);

  return 1;
} // end int FFmpeg_Input::Open( const char * filepath )

int FFmpeg_Input::Close( ) {
  if ( streams ) {
    for ( unsigned int i = 0; i < input_format_context->nb_streams; i += 1 ) {
      avcodec_close(streams[i].context);
#if LIBAVCODEC_VERSION_CHECK(57, 64, 0, 64, 0)
      avcodec_free_context(&streams[i].context);
      streams[i].context = nullptr;
#endif
    }
    delete[] streams;
    streams = nullptr;
  }

  if ( input_format_context ) {
#if !LIBAVFORMAT_VERSION_CHECK(53, 17, 0, 25, 0)
    av_close_input_file(input_format_context);
#else
    avformat_close_input(&input_format_context);
#endif
    input_format_context = nullptr;
  }
  return 1;
} // end int FFmpeg_Input::Close()

AVFrame *FFmpeg_Input::get_frame(int stream_id) {
  int frameComplete = false;
  AVPacket packet;
  av_init_packet(&packet);

  while ( !frameComplete ) {
    int ret = av_read_frame(input_format_context, &packet);
    if ( ret < 0 ) {
      if (
          // Check if EOF.
          (ret == AVERROR_EOF || (input_format_context->pb && input_format_context->pb->eof_reached)) ||
          // Check for Connection failure.
          (ret == -110)
         ) {
        Info("av_read_frame returned %s.", av_make_error_string(ret).c_str());
        return nullptr;
      }
      Error("Unable to read packet from stream %d: error %d \"%s\".",
          packet.stream_index, ret, av_make_error_string(ret).c_str());
      return nullptr;
    }
    ZM_DUMP_STREAM_PACKET(input_format_context->streams[packet.stream_index], packet, "Received packet");

    if ( (stream_id >= 0) && (packet.stream_index != stream_id) ) {
      Debug(1,"Packet is not for our stream (%d)", packet.stream_index );
      continue;
    }

    AVCodecContext *context = streams[packet.stream_index].context;

    if ( frame ) {
      av_frame_free(&frame);
      frame = zm_av_frame_alloc();
    } else {
      frame = zm_av_frame_alloc();
    }
    ret = zm_send_packet_receive_frame(context, frame, packet);
    if ( ret < 0 ) {
      Error("Unable to decode frame at frame %d: %d %s, continuing",
          streams[packet.stream_index].frame_count, ret, av_make_error_string(ret).c_str());
      zm_av_packet_unref(&packet);
      av_frame_free(&frame);
      continue;
    } else {
      if ( is_video_stream(input_format_context->streams[packet.stream_index]) ) {
        zm_dump_video_frame(frame, "resulting video frame");
      } else {
        zm_dump_frame(frame, "resulting frame");
      }
    }

    frameComplete = 1;

    zm_av_packet_unref(&packet);

  } // end while !frameComplete
  return frame;
}  // end AVFrame *FFmpeg_Input::get_frame

AVFrame *FFmpeg_Input::get_frame(int stream_id, double at) {
  Debug(1, "Getting frame from stream %d at %f", stream_id, at);

  int64_t seek_target = (int64_t)(at * AV_TIME_BASE);
  Debug(1, "Getting frame from stream %d at seektarget: %" PRId64, stream_id, seek_target);
  seek_target = av_rescale_q(seek_target, AV_TIME_BASE_Q, input_format_context->streams[stream_id]->time_base);
  Debug(1, "Getting frame from stream %d at %" PRId64, stream_id, seek_target);

  int ret;

  if (!frame) {
    // Don't have a frame yet, so get a keyframe before the timestamp
    ret = av_seek_frame(input_format_context, stream_id, seek_target, AVSEEK_FLAG_FRAME);
    if (ret < 0) {
      Error("Unable to seek in stream");
      return nullptr;
    }
    // Have to grab a frame to update our current frame to know where we are
    get_frame(stream_id);

    if (!frame) {
      Warning("Unable to get frame.");
      return nullptr;
    }
  }  // end if ! frame

  if ( 
			(last_seek_request >= 0)
			&&
			(last_seek_request > seek_target) 
			&&
			(frame->pts > seek_target)
		 ) {
    zm_dump_frame(frame, "frame->pts > seek_target, seek backwards");
  // our frame must be beyond our seek target. so go backwards to before it
    if (( ret = av_seek_frame(input_format_context, stream_id, seek_target, 
            AVSEEK_FLAG_BACKWARD | AVSEEK_FLAG_FRAME
            ) ) < 0) {
      Error("Unable to seek in stream %d", ret);
      return nullptr;
    }
    // Have to grab a frame to update our current frame to know where we are
    get_frame(stream_id);
    if ( is_video_stream(input_format_context->streams[stream_id]) ) {
      zm_dump_video_frame(frame, "frame->pts > seek_target, got");
    } else {
      zm_dump_frame(frame, "frame->pts > seek_target, got");
    }
  } else if ( last_seek_request == seek_target ) {
    // paused case, sending keepalives
    return frame;
  } // end if frame->pts > seek_target

	last_seek_request = seek_target;

  // Seeking seems to typically seek to a keyframe, so then we have to decode until we get the frame we want.
  if ( frame->pts <= seek_target ) {
    if ( is_video_stream(input_format_context->streams[stream_id]) ) {
      zm_dump_video_frame(frame, "pts <= seek_target");
    } else {
      zm_dump_frame(frame, "pts <= seek_target");
    }
    while ( frame && (frame->pts < seek_target) ) {
      if ( !get_frame(stream_id) ) {
        Warning("Got no frame. returning nothing");
        return frame;
      }
    }
    zm_dump_frame(frame, "frame->pts <= seek_target, got");
    return frame;
  }

  return get_frame(stream_id);
}  // end AVFrame *FFmpeg_Input::get_frame( int stream_id, struct timeval at)