虽然FFmpeg本身有cuvid硬解，但是找不到什么好的资料，英伟达的SDK比较容易懂，参考FFmpeg源码，将NVIDIA VIDEO CODEC SDK的数据获取改为FFmpeg获取，弥补原生SDK不能以流作为数据源的不足。所用SDK版本为Video_Codec_SDK_7.1.9，英伟达官网可下载。
1.修改数据源
首先是FFmpeg的一些常规的初始化
bool VideoSource::init(const std::string sFileName, FrameQueue *pFrameQueue)
{
assert(0 != pFrameQueue);
oSourceData_.hVideoParser = 0;
oSourceData_.pFrameQueue = pFrameQueue; int i;
AVCodec *pCodec; av_register_all();
avformat_network_init();
pFormatCtx = avformat_alloc_context(); if (avformat_open_input(&pFormatCtx, sFileName.c_str(), NULL, NULL) != 0){
printf("Couldn't open input stream.\n");
return false;
}
if (avformat_find_stream_info(pFormatCtx, NULL)<0){
printf("Couldn't find stream information.\n");
return false;
}
videoindex = -1;
for (i = 0; i<pFormatCtx->nb_streams; i++)
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO){
videoindex = i;
break;
} if (videoindex == -1){
printf("Didn't find a video stream.\n");
return false;
} pCodecCtx = pFormatCtx->streams[videoindex]->codec; pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL){
printf("Codec not found.\n");
return false;
} //Output Info-----------------------------
printf("--------------- File Information ----------------\n");
av_dump_format(pFormatCtx, 0, sFileName.c_str(), 0);
printf("-------------------------------------------------\n"); memset(&g_stFormat, 0, sizeof(CUVIDEOFORMAT)); switch (pCodecCtx->codec_id) {
case AV_CODEC_ID_H263:
g_stFormat.codec = cudaVideoCodec_MPEG4;
break; case AV_CODEC_ID_H264:
g_stFormat.codec = cudaVideoCodec_H264;
break; case AV_CODEC_ID_HEVC:
g_stFormat.codec = cudaVideoCodec_HEVC;
break; case AV_CODEC_ID_MJPEG:
g_stFormat.codec = cudaVideoCodec_JPEG;
break; case AV_CODEC_ID_MPEG1VIDEO:
g_stFormat.codec = cudaVideoCodec_MPEG1;
break; case AV_CODEC_ID_MPEG2VIDEO:
g_stFormat.codec = cudaVideoCodec_MPEG2;
break; case AV_CODEC_ID_MPEG4:
g_stFormat.codec = cudaVideoCodec_MPEG4;
break; case AV_CODEC_ID_VP8:
g_stFormat.codec = cudaVideoCodec_VP8;
break; case AV_CODEC_ID_VP9:
g_stFormat.codec = cudaVideoCodec_VP9;
break; case AV_CODEC_ID_VC1:
g_stFormat.codec = cudaVideoCodec_VC1;
break;
default:
return false;
} //这个地方的FFmoeg与cuvid的对应关系不是很确定，不过用这个参数似乎最靠谱
switch (pCodecCtx->sw_pix_fmt)
{
case AV_PIX_FMT_YUV420P:
g_stFormat.chroma_format = cudaVideoChromaFormat_420;
break;
case AV_PIX_FMT_YUV422P:
g_stFormat.chroma_format = cudaVideoChromaFormat_422;
break;
case AV_PIX_FMT_YUV444P:
g_stFormat.chroma_format = cudaVideoChromaFormat_444;
break;
default:
g_stFormat.chroma_format = cudaVideoChromaFormat_420;
break;
} //找了好久，总算是找到了FFmpeg中标识场格式和帧格式的标识位
//场格式是隔行扫描的，需要做去隔行处理
switch (pCodecCtx->field_order)
{
case AV_FIELD_PROGRESSIVE:
case AV_FIELD_UNKNOWN:
g_stFormat.progressive_sequence = true;
break;
default:
g_stFormat.progressive_sequence = false;
break;
} pCodecCtx->thread_safe_callbacks = 1; g_stFormat.coded_width = pCodecCtx->coded_width;
g_stFormat.coded_height = pCodecCtx->coded_height; g_stFormat.display_area.right = pCodecCtx->width;
g_stFormat.display_area.left = 0;
g_stFormat.display_area.bottom = pCodecCtx->height;
g_stFormat.display_area.top = 0; if (pCodecCtx->codec_id == AV_CODEC_ID_H264 || pCodecCtx->codec_id == AV_CODEC_ID_HEVC) {
if (pCodecCtx->codec_id == AV_CODEC_ID_H264)
h264bsfc = av_bitstream_filter_init("h264_mp4toannexb");
else
h264bsfc = av_bitstream_filter_init("hevc_mp4toannexb");
} return true;
}
这里面非常重要的一段代码是
if (pCodecCtx->codec_id == AV_CODEC_ID_H264 || pCodecCtx->codec_id == AV_CODEC_ID_HEVC) {
if (pCodecCtx->codec_id == AV_CODEC_ID_H264)
h264bsfc = av_bitstream_filter_init("h264_mp4toannexb");
else
h264bsfc = av_bitstream_filter_init("hevc_mp4toannexb");
}网上有许多代码和伪代码都说实现了把数据源修改为FFmpeg，但我在尝试的时候发现cuvidCreateVideoParser创建的Parser的回调函数都没有调用。经过一番折腾，综合英伟达网站、stackoverflow和FFmpeg源码，才发现对H264数据要做一个处理才能把AVPacket有效的转为CUVIDSOURCEDATAPACKET。其中h264bsfc的定义为AVBitStreamFilterContext* h264bsfc = NULL;
2.AVPacket转CUVIDSOURCEDATAPACKET,并交给cuvidParseVideoData
void VideoSource::play_thread(LPVOID lpParam)
{
AVPacket *avpkt;
avpkt = (AVPacket *)av_malloc(sizeof(AVPacket));
CUVIDSOURCEDATAPACKET cupkt;
int iPkt = 0;
CUresult oResult;
while (av_read_frame(pFormatCtx, avpkt) >= 0){
if (bThreadExit){
break;
}
bStarted = true;
if (avpkt->stream_index == videoindex){ cuCtxPushCurrent(g_oContext); if (avpkt && avpkt->size) {
if (h264bsfc)
{
av_bitstream_filter_filter(h264bsfc, pFormatCtx->streams[videoindex]->codec, NULL, &avpkt->data, &avpkt->size, avpkt->data, avpkt->size, 0);
} cupkt.payload_size = (unsigned long)avpkt->size;
cupkt.payload = (const unsigned char*)avpkt->data; if (avpkt->pts != AV_NOPTS_VALUE) {
cupkt.flags = CUVID_PKT_TIMESTAMP;
if (pCodecCtx->pkt_timebase.num && pCodecCtx->pkt_timebase.den){
AVRational tb;
tb.num = 1;
tb.den = AV_TIME_BASE;
cupkt.timestamp = av_rescale_q(avpkt->pts, pCodecCtx->pkt_timebase, tb);
}
else
cupkt.timestamp = avpkt->pts;
}
}
else {
cupkt.flags = CUVID_PKT_ENDOFSTREAM;
} oResult = cuvidParseVideoData(oSourceData_.hVideoParser, &cupkt);
if ((cupkt.flags & CUVID_PKT_ENDOFSTREAM) || (oResult != CUDA_SUCCESS)){
break;
}
iPkt++;
//printf("Succeed to read avpkt %d !\n", iPkt);
checkCudaErrors(cuCtxPopCurrent(NULL));
}
av_free_packet(avpkt);
} oSourceData_.pFrameQueue->endDecode();
bStarted = false;
}
这里FFmpeg读取数据包后，对H264和HEVC格式，有一个重要的处理，就是前面提到的，
if (h264bsfc)
{
av_bitstream_filter_filter(h264bsfc, pFormatCtx->streams[videoindex]->codec, NULL, &avpkt->data, &avpkt->size, avpkt->data, avpkt->size, 0);
}
这个处理的含义见雷霄华的博客http://blog.csdn.net/leixiaohua1020/article/details/39767055。
这样，通过FFmpeg，CUVID就可以对流进行处理了。个人尝试过读取本地文件和rtsp流。FFmpeg读取rtsp流的方式竟然只需要把文件改为rtsp流的地址就可以，以前没做过流式的，我还以为会很复杂的。
3.一点数据
这是在GTX 1080上把解码进程（没做显示）开了20路解码得到的数据。20路1920X1080解码还能到平局37fps，这显卡也是6得不行。