将 h264_cuvid 解码器与 ffmpeg 一起使用时出错答案

【问题标题】：Error while using h264_cuvid decoder with ffmpeg将 h264_cuvid 解码器与 ffmpeg 一起使用时出错
【发布时间】：2017-11-02 21:27:41
【问题描述】：

我正在尝试使用带有 ffmpeg 的 NVIDIA cuvid 硬件加速来解码视频。

我使用的是 NVIDIA GeForce GT 745M 显卡 (GPU:GK107)，它与 NVIDIA here 指定的 cuvid 兼容

我用以下标志编译了 ffmpeg：

./configure --enable-cuda --enable-nvenc --enable-cuvid

然后，我使用 ffmpeg 和以下命令行：

ffmpeg.exe -hwaccel cuvid -c:v h264_cuvid -i video.mkv video.mkv

ffmpeg完成，似乎无法打开cuvid函数：

Cannot load cuvidGetDecoderCaps
[h264_cuvid @ 07047b80] Failed loading nvcuvid.
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (libx264))
  Stream #0:1 -> #0:1 (ac3 (native) -> vorbis (libvorbis))
  Stream #0:3 -> #0:2 (subrip (srt) -> ass (ssa))
Error while opening decoder for input stream #0:0 : Unknown error occurred

在ffmpeg源码中，我可以发现这个错误信息是由下面的宏打印出来的：

#define LOAD_SYMBOL(fun, tp, symbol)                                \
    do {                                                            \
        if (!((f->fun) = (tp*)dlsym(f->lib, symbol))) {             \
            av_log(NULL, AV_LOG_ERROR, "Cannot load %s\n", symbol); \
            ret = AVERROR_UNKNOWN;                                  \
            goto error;                                             \
        }                                                           \
        av_log(NULL, AV_LOG_TRACE, "Loaded sym: %s\n", symbol);     \
    } while (0)

调用者：

static inline int cuvid_load_functions(CuvidFunctions **functions)
{
    GENERIC_LOAD_FUNC_PREAMBLE(CuvidFunctions, cuvid, NVCUVID_LIBNAME);

    LOAD_SYMBOL(cuvidGetDecoderCaps, tcuvidGetDecoderCaps, "cuvidGetDecoderCaps");
    LOAD_SYMBOL(cuvidCreateDecoder, tcuvidCreateDecoder, "cuvidCreateDecoder");
    LOAD_SYMBOL(cuvidDestroyDecoder, tcuvidDestroyDecoder, "cuvidDestroyDecoder");
    LOAD_SYMBOL(cuvidDecodePicture, tcuvidDecodePicture, "cuvidDecodePicture");
#ifdef __CUVID_DEVPTR64
    LOAD_SYMBOL(cuvidMapVideoFrame, tcuvidMapVideoFrame, "cuvidMapVideoFrame64");
    LOAD_SYMBOL(cuvidUnmapVideoFrame, tcuvidUnmapVideoFrame, "cuvidUnmapVideoFrame64");
#else
    LOAD_SYMBOL(cuvidMapVideoFrame, tcuvidMapVideoFrame, "cuvidMapVideoFrame");
    LOAD_SYMBOL(cuvidUnmapVideoFrame, tcuvidUnmapVideoFrame, "cuvidUnmapVideoFrame");
#endif
    LOAD_SYMBOL(cuvidCtxLockCreate, tcuvidCtxLockCreate, "cuvidCtxLockCreate");
    LOAD_SYMBOL(cuvidCtxLockDestroy, tcuvidCtxLockDestroy, "cuvidCtxLockDestroy");
    LOAD_SYMBOL(cuvidCtxLock, tcuvidCtxLock, "cuvidCtxLock");
    LOAD_SYMBOL(cuvidCtxUnlock, tcuvidCtxUnlock, "cuvidCtxUnlock");

    LOAD_SYMBOL(cuvidCreateVideoSource, tcuvidCreateVideoSource, "cuvidCreateVideoSource");
    LOAD_SYMBOL(cuvidCreateVideoSourceW, tcuvidCreateVideoSourceW, "cuvidCreateVideoSourceW");
    LOAD_SYMBOL(cuvidDestroyVideoSource, tcuvidDestroyVideoSource, "cuvidDestroyVideoSource");
    LOAD_SYMBOL(cuvidSetVideoSourceState, tcuvidSetVideoSourceState, "cuvidSetVideoSourceState");
    LOAD_SYMBOL(cuvidGetVideoSourceState, tcuvidGetVideoSourceState, "cuvidGetVideoSourceState");
    LOAD_SYMBOL(cuvidGetSourceVideoFormat, tcuvidGetSourceVideoFormat, "cuvidGetSourceVideoFormat");
    LOAD_SYMBOL(cuvidGetSourceAudioFormat, tcuvidGetSourceAudioFormat, "cuvidGetSourceAudioFormat");
    LOAD_SYMBOL(cuvidCreateVideoParser, tcuvidCreateVideoParser, "cuvidCreateVideoParser");
    LOAD_SYMBOL(cuvidParseVideoData, tcuvidParseVideoData, "cuvidParseVideoData");
    LOAD_SYMBOL(cuvidDestroyVideoParser, tcuvidDestroyVideoParser, "cuvidDestroyVideoParser");

    GENERIC_LOAD_FUNC_FINALE(cuvid);
}

有人知道 cuvid 是否需要特定文件来加载其功能吗？这里有什么问题的线索吗？

【问题讨论】：

标签： ffmpeg h.264 cuvid

【解决方案1】：

我没有问题了。

我在 ffmpeg 编译期间忘记使用 libnpp。

我目前的配置是：

./configure --enable-cuda --enable-nvenc --enable-cuvid --enable-libnpp --extra-cflags=-I<path_to_libnpp_headers> --extra-ldflags=-L<path_to_libnpp_libraries>

【讨论】：