avcodec_decode_video2 RETURNS THE VALUE -1094995529 in the threaded function

Question

I am developing rtsp streaming player, and followed the below approach.

1) Read packet, decode, display -> works perfectly.

while (1) {
    if ( av_read_frame(pFormatCtx, &packet) >= 0) {
        if (packet.stream_index == videoStream) {
            retDecoder = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
            if  ( retDecoder <= 0)
                LOGD (" Unable to Decode...retval %d ", retDecoder);
            if (frameFinished) {
            }
        }
        av_free_packet (&packet);
    }
}

Whereas,

I introduced two threads, one is reading and pushing into the queue and the second one is reading from the queue.

My problem is while reading the same packet, and decode, i m unable to decode, the return value of the av_video_decode2 is -1094995529.

Below is the short description of code. Kindly help to solve this issue?.

AVPacketList *firstNode=NULL, *lastNode=NULL;

int pushPacket (AVPacket * pkt)
{
    AVPacketList *newNode = av_malloc(sizeof(AVPacketList));
    newNode->pkt = *pkt;
    newNode->next = NULL;

    SDL_LockMutex (rwMutex);

    if (lastNode != NULL )  {
        lastNode->next = newNode;
        lastNode = newNode;
    } else {
        firstNode = lastNode = newNode;
    }

 SDL_UnlockMutex (rwMutex);
}

int pullPacket ()
{
    AVPacketList *tempNode;
    AVPacket *pkt;
    int res=0;

    SDL_LockMutex (rwMutex);
    if ( firstNode != NULL ) {
        tempNode = firstNode;
        *pkt = tempNode->pkt;
        res = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, pkt);  // HERE IS THE PROBLEM.
        if (frameFinished) {
            LOGD (" fRAME DECODED.. %d \n", counter++);
        }

        if (firstNode->next != NULL) {   
            firstNode = firstNode->next;
        }
        else {
            firstNode = NULL;
            lastNode = NULL;
        }
        av_free (tempNode);
    }
}

In Thread 1:

int PacketReader (void *ptr)
{
    AVPacket pkt1, *rpacket;
    rpacket = &pkt1;
    while (globalQuit != 0)  {
        if ( av_read_frame(pFormatCtx, rpacket) >= 0) {
            if (packet.stream_index == videoStream) {
                pushPacket (rpacket);
            }
            av_free_packet(rpacket);
        }
    }
}

In thread 2:

while (1) {
   pullPacket ();
}

Answer 1

The error code you have can be decoded as follows. The error codes from ffmpeg (error.h from avutil) : http://ffmpeg.org/doxygen/trunk/error_8h_source.html

It turns out the value you specified is :

#define AVERROR_INVALIDDATA        FFERRTAG( 'I','N','D','A')

The -1094995529 becomes -0x41444E49 and when you look at those letters, in ACSII, 0x41 = 'A', 0x44 = 'D', 0x4E = 'N, and 0x49 = 'I'. Due to the macro/etc things are reversed, so ADNI becomes INDA, which you can see from the #define snippet, is the AVERROR_INVALIDDATA defined FFERRTAG( 'I','N','D','A').

The rest of the error codes are in that file and I've pasted them below here :

#define AVERROR_BSF_NOT_FOUND      FFERRTAG(0xF8,'B','S','F') ///< Bitstream filter not found
#define AVERROR_BUG                FFERRTAG( 'B','U','G','!') ///< Internal bug, also see AVERROR_BUG2
#define AVERROR_BUFFER_TOO_SMALL   FFERRTAG( 'B','U','F','S') ///< Buffer too small
#define AVERROR_DECODER_NOT_FOUND  FFERRTAG(0xF8,'D','E','C') ///< Decoder not found
#define AVERROR_DEMUXER_NOT_FOUND  FFERRTAG(0xF8,'D','E','M') ///< Demuxer not found
#define AVERROR_ENCODER_NOT_FOUND  FFERRTAG(0xF8,'E','N','C') ///< Encoder not found
#define AVERROR_EOF                FFERRTAG( 'E','O','F',' ') ///< End of file
#define AVERROR_EXIT               FFERRTAG( 'E','X','I','T') ///< Immediate exit was requested; the called function should not be restarted
#define AVERROR_EXTERNAL           FFERRTAG( 'E','X','T',' ') ///< Generic error in an external library
#define AVERROR_FILTER_NOT_FOUND   FFERRTAG(0xF8,'F','I','L') ///< Filter not found
#define AVERROR_INVALIDDATA        FFERRTAG( 'I','N','D','A') ///< Invalid data found when processing input
#define AVERROR_MUXER_NOT_FOUND    FFERRTAG(0xF8,'M','U','X') ///< Muxer not found
#define AVERROR_OPTION_NOT_FOUND   FFERRTAG(0xF8,'O','P','T') ///< Option not found
#define AVERROR_PATCHWELCOME       FFERRTAG( 'P','A','W','E') ///< Not yet implemented in FFmpeg, patches welcome
#define AVERROR_PROTOCOL_NOT_FOUND FFERRTAG(0xF8,'P','R','O') ///< Protocol not found
#define AVERROR_STREAM_NOT_FOUND   FFERRTAG(0xF8,'S','T','R') ///< Stream not found
#define AVERROR_BUG2               FFERRTAG( 'B','U','G',' ')
#define AVERROR_UNKNOWN            FFERRTAG( 'U','N','K','N') ///< Unknown error, typically from an external library
#define AVERROR_EXPERIMENTAL       (-0x2bb2afa8) ///< Requested feature is flagged experimental. Set strict_std_compliance if you really want to use it.
#define AVERROR_INPUT_CHANGED      (-0x636e6701) ///< Input changed between calls. Reconfiguration is required. (can be OR-ed with AVERROR_OUTPUT_CHANGED)
#define AVERROR_OUTPUT_CHANGED     (-0x636e6702) ///< Output changed between calls. Reconfiguration is required. (can be OR-ed with AVERROR_INPUT_CHANGED)
#define AVERROR_HTTP_BAD_REQUEST   FFERRTAG(0xF8,'4','0','0')
#define AVERROR_HTTP_UNAUTHORIZED  FFERRTAG(0xF8,'4','0','1')
#define AVERROR_HTTP_FORBIDDEN     FFERRTAG(0xF8,'4','0','3')
#define AVERROR_HTTP_NOT_FOUND     FFERRTAG(0xF8,'4','0','4')
#define AVERROR_HTTP_OTHER_4XX     FFERRTAG(0xF8,'4','X','X')
#define AVERROR_HTTP_SERVER_ERROR  FFERRTAG(0xF8,'5','X','X')

As for your actual bug, I assume you've fixed it by now, but the AVPacket structure contains pointers and buffers and such. While you could deallocate the packet structure space, you can't use av_free_packet() on it as that goes down and deallocs the internals.

Answer 2

In your Thread 1, you unconditionally free rpacket. Instead, you should not free the packet when adding it to your queue and only free it when Thread 2 is done with it...

Not sure this is everything that is wrong with this, though. I stopped looking after seeing the above.