花时间研究了一些ffmpeg的nvenc，本来想我已经有了cuvid，然后又搞出来了nvenc，应该可以做个全套的英伟达的转码了，没想到ffmpeg官网下载的动态库没有cuvid，windows上编译cuvid又老是出错，忧了个伤。
1.nvenc编码
h264_nvenc是很容易调出来的，把编码器ffmpeg源码自带的例子的编码器换成h264_nvenc就行了。可是hevc_nvenc就花了我好多时间，感觉调试技术还是差了好多。
#include "stdafx.h" /* * Video encoding example */ static void video_encode_example(const char *filename) { AVCodec *codec; AVCodecContext *c = NULL; int i, ret, x, y, got_output; AVFrame *frame; AVPacket pkt; uint8_t endcode[] = { 0, 0, 1, 0xb7 }; av_log_set_level(64); //AVBufferRef *device_ref = NULL; //AVBufferRef *hw_frames_ctx = NULL; //hw_frames_ctx = (AVBufferRef *)av_mallocz(sizeof(AVBufferRef)); //if (!hw_frames_ctx) { // ret = AVERROR(ENOMEM); // return ; //} //ret = av_hwdevice_ctx_create(&device_ref, AV_HWDEVICE_TYPE_CUDA,"CUDA", NULL, 0); //if (ret < 0) // return; //hw_frames_ctx = av_hwframe_ctx_alloc(device_ref); //if (!hw_frames_ctx) { // av_log(NULL, AV_LOG_ERROR, "av_hwframe_ctx_alloc failed\n"); // ret = AVERROR(ENOMEM); // return; //} //av_buffer_unref(&device_ref); //c->hw_frames_ctx = av_buffer_ref(hw_frames_ctx); //if (!hw_frames_ctx) { // av_log(NULL, AV_LOG_ERROR, "av_buffer_ref failed\n"); // ret = AVERROR(ENOMEM); // return; //} printf("Encode video file %s\n", filename); /* find the video encoder */ codec = avcodec_find_encoder_by_name("hevc_nvenc"); //codec = avcodec_find_encoder(AV_CODEC_ID_H265); //codec = avcodec_find_encoder_by_name("h264_nvenc"); //codec = avcodec_find_encoder(AV_CODEC_ID_H264); if (!codec) { fprintf(stderr, "Codec not found\n"); exit(1); } c = avcodec_alloc_context3(codec); if (!c) { fprintf(stderr, "Could not allocate video codec context\n"); exit(1); } /* put sample parameters */ c->bit_rate = 400000; /* resolution must be a multiple of two */ c->width = 352; c->height = 288; /* frames per second */ c->time_base.num = 1; c->time_base.den = 25; /* emit one intra frame every ten frames * check frame pict_type before passing frame * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I * then gop_size is ignored and the output of encoder * will always be I frame irrespective to gop_size */ c->gop_size = 10; c->max_b_frames = 1; c->pix_fmt = AV_PIX_FMT_YUV420P;//AV_PIX_FMT_CUDA; c->max_b_frames = 0; AVDictionary *param = 0; //H.264 if (codec->id == AV_CODEC_ID_H264) { av_dict_set(¶m, "preset", "medium", 0); av_dict_set(¶m, "tune", "zerolatency", 0); } //H.265 if (codec->id == AV_CODEC_ID_H265 || codec->id == AV_CODEC_ID_HEVC){ //av_dict_set(¶m, "x265-params", "qp=20", 0); av_dict_set(¶m, "x265-params", "crf=25", 0); av_dict_set(¶m, "preset", "fast", 0); av_dict_set(¶m, "tune", "zero-latency", 0); } /* open it */ if (avcodec_open2(c, codec, ¶m) < 0) { fprintf(stderr, "Could not open codec\n"); system("pause"); exit(1); } FILE *f; f = fopen(filename, "wb"); if (!f) { fprintf(stderr, "Could not open %s\n", filename); exit(1); } frame = av_frame_alloc(); if (!frame) { fprintf(stderr, "Could not allocate video frame\n"); exit(1); } frame->format = c->pix_fmt; frame->width = c->width; frame->height = c->height; /* the image can be allocated by any means and av_image_alloc() is * just the most convenient way if av_malloc() is to be used */ ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height, c->pix_fmt, 32); if (ret < 0) { fprintf(stderr, "Could not allocate raw picture buffer\n"); exit(1); } /* encode 1 second of video */ for (i = 0; i < 500; i++) { av_init_packet(&pkt); pkt.data = NULL; // packet data will be allocated by the encoder pkt.size = 0; fflush(stdout); /* prepare a dummy image */ /* Y */ for (y = 0; y < c->height; y++) { for (x = 0; x < c->width; x++) { frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3; } } /* Cb and Cr */ for (y = 0; y < c->height / 2; y++) { for (x = 0; x < c->width / 2; x++) { frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2; frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5; } } frame->pts = i; /* encode the image */ ret = avcodec_encode_video2(c, &pkt, frame, &got_output); if (ret < 0) { fprintf(stderr, "Error encoding frame\n"); exit(1); } if (got_output) { printf("Write frame %3d (size=%5d)\n", i, pkt.size); fwrite(pkt.data, 1, pkt.size, f); av_packet_unref(&pkt); } } /* get the delayed frames */ for (got_output = 1; got_output; i++) { fflush(stdout); ret = avcodec_encode_video2(c, &pkt, NULL, &got_output); if (ret < 0) { fprintf(stderr, "Error encoding frame\n"); exit(1); } if (got_output) { printf("Write frame %3d (size=%5d)\n", i, pkt.size); fwrite(pkt.data, 1, pkt.size, f); av_packet_unref(&pkt); } } /* add sequence end code to have a real MPEG file */ fwrite(endcode, 1, sizeof(endcode), f); fclose(f); avcodec_close(c); av_free(c); av_freep(&frame->data[0]); av_frame_free(&frame); printf("\n"); } int main(int argc, char **argv) { /* register all the codecs */ avcodec_register_all(); avcodec_register_all(); avdevice_register_all(); avfilter_register_all(); av_register_all(); avformat_network_init(); video_encode_example("test.hevc"); system("pause"); return 0; }
代码中av_log_set_level(64);可以帮助输出中间信息，参数可以自行设置，参数为越大，能输出的信息等级越多，我的问题就是通过这个函数知道的，然后到源码中找对应处才最终解决。编码器为hevc_nvenc时max_b_frames必须为0，即代码中的 c->max_b_frames = 0;另外c->pix_fmt = AV_PIX_FMT_YUV420P;//AV_PIX_FMT_CUDA;这行代码需要注意，设置为AV_PIX_FMT_YUV420P意味着数据是从内存读取的，设置为AV_PIX_FMT_CUDA意味着数据在显存中，AV_PIX_FMT_CUDA与cuvid是一起的，只有编出来的ffmpeg支持cuvid时AV_PIX_FMT_CUDA才有效。
2.用nvenc做转码
由于还没有编出支持cuvid的ffmpeg，所以解码这里就先不用cuvid了，用CPU来解码。其实这样有一个好处，就是对格式的要求低，cuvid对格式的输入是有要求的，用这种方法所有用ffmpeg解码后的数据都可以用nvenc来编码，缺点当然是这样比较慢了。
#include "stdafx.h" #include#include /* * Video encoding example */ static void video_encode_example(const char *filename) { AVCodec *codec; AVCodecContext *c = NULL; int i, ret, x, y, got_output; AVPacket pkt; uint8_t endcode[] = { 0, 0, 1, 0xb7 }; av_log_set_level(64); AVFormatContext *pFormatCtx; int videoindex; AVCodecContext *pCodecCtx; AVCodec *pCodec; AVFrame *pFrame, *pFrameYUV; uint8_t *out_buffer; char filepath[] = "H:\\nvenc\\灿烂人生1280.rmvb"; av_register_all(); avformat_network_init(); pFormatCtx = avformat_alloc_context(); if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) != 0){ printf("Couldn't open input stream.\n"); return ; } if (avformat_find_stream_info(pFormatCtx, NULL)<0){ printf("Couldn't find stream information.\n"); return ; } videoindex = -1; for (i = 0; i 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 ; } pCodecCtx = pFormatCtx->streams[videoindex]->codec; pCodec = avcodec_find_decoder(pCodecCtx->codec_id); if (pCodec == NULL){ printf("Codec not found.\n"); return ; } if (avcodec_open2(pCodecCtx, pCodec, NULL)<0){ printf("Could not open codec.\n"); return ; } pFrame = av_frame_alloc(); pFrameYUV = av_frame_alloc(); out_buffer = (uint8_t *)av_malloc(avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height)); avpicture_fill((AVPicture *)pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height); //Output Info----------------------------- printf("--------------- File Information ----------------\n"); av_dump_format(pFormatCtx, 0, filepath, 0); printf("-------------------------------------------------\n"); struct SwsContext *img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL); printf("Encode video file %s\n", filename); /* find the video encoder */ codec = avcodec_find_encoder_by_name("hevc_nvenc"); //codec = avcodec_find_encoder(AV_CODEC_ID_H265); //codec = avcodec_find_encoder_by_name("h264_nvenc"); //codec = avcodec_find_encoder(AV_CODEC_ID_H264); if (!codec) { fprintf(stderr, "Codec not found\n"); exit(1); } c = avcodec_alloc_context3(codec); if (!c) { fprintf(stderr, "Could not allocate video codec context\n"); exit(1); } /* put sample parameters */ c->bit_rate = pCodecCtx->bit_rate; /* resolution must be a multiple of two */ c->width = pCodecCtx->width; c->height = pCodecCtx->height; c->time_base = pCodecCtx->time_base; c->gop_size = pCodecCtx->gop_size; c->pix_fmt = AV_PIX_FMT_YUV420P; c->max_b_frames = 0; AVDictionary *param = 0; //H.264 if (codec->id == AV_CODEC_ID_H264) { av_dict_set(¶m, "preset", "medium", 0); av_dict_set(¶m, "tune", "zerolatency", 0); } //H.265 if (codec->id == AV_CODEC_ID_H265 || codec->id == AV_CODEC_ID_HEVC){ //av_dict_set(¶m, "x265-params", "qp=20", 0); av_dict_set(¶m, "x265-params", "crf=25", 0); av_dict_set(¶m, "preset", "fast", 0); av_dict_set(¶m, "tune", "zero-latency", 0); } /* open it */ if (avcodec_open2(c, codec, ¶m) < 0) { fprintf(stderr, "Could not open codec\n"); system("pause"); exit(1); } FILE *f; f = fopen(filename, "wb"); if (!f) { fprintf(stderr, "Could not open %s\n", filename); exit(1); } AVPacket *packet; packet = (AVPacket *)av_malloc(sizeof(AVPacket)); int got_picture; int iCount = 0; int64_t iStart = av_gettime(); while (av_read_frame(pFormatCtx, packet) >= 0){ if (packet->stream_index == videoindex){ ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet); if (ret < 0){ printf("Decode Error.\n"); return ; } if (got_picture){ sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize); av_init_packet(&pkt); pkt.data = NULL; // packet data will be allocated by the encoder pkt.size = 0; pFrameYUV->width = c->width; pFrameYUV->height = c->height; pFrameYUV->format = c->pix_fmt; /* encode the image */ ret = avcodec_encode_video2(c, &pkt, pFrameYUV, &got_output); if (ret < 0) { fprintf(stderr, "Error encoding frame\n"); exit(1); } if (got_output) { iCount++; fwrite(pkt.data, 1, pkt.size, f); av_packet_unref(&pkt); if (iCount % 1000 == 0) { printf("1000帧用时：%d 平均每秒 %f 帧 \n", (av_gettime() - iStart)/100000, (double)1000 * 1000000 / (av_gettime() - iStart)); printf("Write frame %3d (size=%5d)\n", i, pkt.size); int fd = _fileno(f); //获取文件描述符 _commit(fd); iStart = av_gettime(); } } } } av_free_packet(packet); } /* get the delayed frames */ for (got_output = 1; got_output; i++) { fflush(stdout); ret = avcodec_encode_video2(c, &pkt, NULL, &got_output); if (ret < 0) { fprintf(stderr, "Error encoding frame\n"); exit(1); } if (got_output) { printf("Write frame %3d (size=%5d)\n", i, pkt.size); fwrite(pkt.data, 1, pkt.size, f); av_packet_unref(&pkt); } } /* add sequence end code to have a real MPEG file */ fwrite(endcode, 1, sizeof(endcode), f); fclose(f); avcodec_close(c); av_free(c); printf("\n"); } int main(int argc, char **argv) { /* register all the codecs */ avcodec_register_all(); avcodec_register_all(); avdevice_register_all(); avfilter_register_all(); av_register_all(); avformat_network_init(); video_encode_example("H:\\nvenc\\test.hevc"); system("pause"); return 0; }
上面用nvenc编出来的并没有封装成文件。h264格式potplayer还可以直接播放，hevc格式就不行了。hevc必须先封装，比如封装成mp4文件，然后才能播放。如何封装的例子网上比较多，我这里给个ffmpeg命令行的示例：
ffmpeg -i f:\25国.265 -c:v copy -f mp4 f:\25国.mp4
最后，nvenc对显卡的要求好像比较高，注意查看自己的显卡是否支持nvenc。
工程源码：http://download.csdn.net/download/qq_33892166/9840113
源码的ffmpg是64位的。