Decoder Example

#include "VideoDecoderSimple.h"

CVideoDecoderSimple::CVideoDecoderSimple(AVCodecID decoder)
{
    avcodec_register_all();
    av_register_all();
    av_log_set_level(AV_LOG_DEBUG);

    m_pCodec = avcodec_find_decoder(decoder);
    m_pCodecCtx = avcodec_alloc_context3(m_pCodec);

    if (m_pCodecCtx)
    {
        if (m_pCodec->capabilities & CODEC_CAP_TRUNCATED)
            m_pCodecCtx->flags |= CODEC_FLAG_TRUNCATED;

        m_pCodecCtx->thread_count = 4;
        m_pCodecCtx->thread_type = FF_THREAD_FRAME;
    }

    avcodec_open2(m_pCodecCtx, m_pCodec, 0);
    m_pFrameDecoded = av_frame_alloc();

    frameDecoded = false;
}

CVideoDecoderSimple::~CVideoDecoderSimple()
{
    av_free(m_pFrameDecoded);
    avcodec_close(m_pCodecCtx);

    avformat_network_deinit();
}

bool CVideoDecoderSimple::DecodeStreamData(unsigned char * pData, size_t sz)
{
    AVPacket        packet;
    av_init_packet(&packet);

    packet.data = pData;
    packet.size = (int)sz;
    int framefinished = 0;
    avcodec_send_packet(m_pCodecCtx, &packet);
    if (avcodec_receive_frame(m_pCodecCtx, m_pFrameDecoded) == 0)
    {
        frameDecoded = true;

        ConvertToRGBA();

        return true;
    }

    return false;
}

void CVideoDecoderSimple::ConvertToRGBA()
{
    AVPixelFormat destinationFormat = AV_PIX_FMT_RGBA;
//  AVPixelFormat sourceFormat = AV_PIX_FMT_YUV420P; //AV_PIX_FMT_NV12;
                                                     //     LOG_DEBUG("Converting Frame!");

    if (this->imageConvertContext == NULL)
    {
        //      LOG_DEBUG("Reset image convert context");
        // Allocate pictures and buffers for conversion
        this->imageConvertContext = sws_getContext(
            m_pCodecCtx->width,
            m_pCodecCtx->height,
            m_pCodecCtx->pix_fmt,
            m_pCodecCtx->width,
            m_pCodecCtx->height,
            destinationFormat,
            SWS_BICUBIC,
            NULL, NULL, NULL);
    }

    // NOTICE: It is generally not a good practice to allocate on demand instead on initialization.
    // It this case the edge cases demand it (what happens if width==0 on the first packet?)
    if (this->m_pRGBAFrame == NULL)
    {
        //      LOG_DEBUG("Reset converted pic");
        int size_rgba = av_image_get_buffer_size(destinationFormat, m_pCodecCtx->width, m_pCodecCtx->height, 32);
        this->m_pRGBAFrameBuffer= (uint8_t*)(av_malloc(size_rgba));
        this->m_pRGBAFrame = av_frame_alloc();
        //      avpicture_fill((AVPicture*)convertedPic, convertedPicBuffer, destinationFormat, width, height);
        av_image_fill_arrays(
            this->m_pRGBAFrame->data,
            this->m_pRGBAFrame->linesize,
            this->m_pRGBAFrameBuffer,
            destinationFormat,
            this->m_pCodecCtx->width,
            this->m_pCodecCtx->height,
            32);
    }

    // This is the conversion. We could scale here if we wanted to
    sws_scale(imageConvertContext, this->m_pFrameDecoded->data, m_pFrameDecoded->linesize, 0, m_pCodecCtx->height, m_pRGBAFrame->data, m_pRGBAFrame->linesize);
    m_pRGBAFrame->width = this->m_pCodecCtx->width;
    m_pRGBAFrame->height = this->m_pCodecCtx->height;

}

void CVideoDecoderSimple::GetLastFrame(unsigned char** frame, unsigned int* width, unsigned int* height)
{
    if (frameDecoded)
    {
        //*frame = m_pFrameDecoded->data[0];
        *frame = m_pRGBAFrame->data[0];
        *width = m_pRGBAFrame->width;
        *height = m_pRGBAFrame->height;
        frameDecoded = false;
    }
    else
    {
        *frame = NULL;
        *width = 0;
        *height = 0;
    }
}