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I recently followed this example (https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/vaapi_encode.c) to encode an AVFrame using NVENC (by swapping out AV_PIX_FMT_VAAPI with AV_PIX_FMT_CUDA and h264_vaapi with h264_nvence, among other things). I am now trying to decode the packet that I encoded and converting it to AV_PIX_FMT_YUV420P as such:

AVFrame *frame;
AVCodecContext *context;
AVCodec *codec;

avcodec_register_all();
codec = avcodec_find_decoder(AV_CODEC_ID_H264);

// allocate and set ffmpeg context
context = avcodec_alloc_context3(decoder->codec);

// open capture decoder
avcodec_open2(context, codec, NULL);

// alloc frame format
frame = (AVFrame *) av_frame_alloc();
frame->format = AV_PIX_FMT_CUDA;

// Receive AVPacket here ...

int success;
avcodec_decode_video2(context, frame, &success, &packet);

// Convert to YUV420P

struct SwsContext *sws_ctx = NULL;
sws_ctx = sws_getContext(1920, 1080,
          AV_PIX_FMT_YUV420P, 1920, 1080,
          AV_PIX_FMT_YUV420P,
          SWS_BILINEAR,
          NULL,
          NULL,
          NULL);

I am not able to pass AV_PIX_FMT_CUDA into sws_ctx because it is not supported. Most examples I've found online say to follow this libav example (https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/hw_decode.c). The problem here is that I don't have an NVIDIA GPU on my decoding computer, so I can't create a hardware device as they do in this example. Does anyone have any suggestions on how to convert an AVFrame encoded to a packet using "h264_nvenc" to an AVFrame with format YUV420P? Thanks!

M. Ying
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2 Answers2

0

You don't have to have GPU to perform decoding an h264 video. CPU decoding (h264) should be just fine. What you mention is about HW Accelerated decoding. No GPU no "hw accelerated" decoding.

Same goes for encoding. You don't have GPU for that either, the software codec (libx264) will work just fine. And you can decode it using either with CPU or GPU.

the kamilz
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0

  1. If possible, use VDPAU. Just modify the sample with vaapi to work with vdpau (to decode)

  2. If you want to use the codec from NVIDIA, you can use the codec search by name, for example h264_cuvid and work with it as with a normal codec. For example "h264_cuvid"

coder80
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