[libav-api] Custom AVIOContext Problems

[Mark Kenna]

Hi All

I am trying to implement a buffered solution using AVIOContext and 
AVFifoBuffer but I am getting an AccessViolationException on the call to 
"avformat_open_input".

Here is the read_packet method

static int read_packet(void *opaque, uint8_t *buf, int buf_size)
{
    AVFifoBuffer *circularBuf = (AVFifoBuffer*)opaque;
    int amountInBuffer = av_fifo_size(circularBuf);

    if (amountInBuffer >= buf_size)
        av_fifo_generic_read(circularBuf, buf, buf_size, NULL);

    amountInBuffer = av_fifo_size(circularBuf);

    return buf_size;
}

And here is the logic that's failing (last line throws the Exception)
    //load FFMPEG
    av_register_all();
    avdevice_register_all();

    //allocate a FormatContext and a circular buffer for handling user 
data
    AVFormatContext *context = avformat_alloc_context();
    circularBuf = av_fifo_alloc(1024 * 1024 * 10);

    //allocate FFMPEG's data buffer and create the IOContext for 
custom data I/O
    uint8_t *buffer = (uint8_t*)av_malloc(bufferSize);
    AVIOContext *ioContext = avio_alloc_context(buffer, bufferSize, 0, 
circularBuf, read_packet, NULL, NULL);
    ioContext->seekable = 0;

    context->pb = ioContext;
    formatContext = context;

    AddData(data, 0);

    //FFMPEG will start reading from the buffer from here
    int err = avformat_open_input(&context, NULL, NULL, NULL);

I have tried various data input (flv, mpeg4, image,...) but they all 
fail with the same thing.

Is there something else I should be doing?

Thanks guys,
Mark.


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