另一篇：ffmpeg硬编解码 Inter QSV
常见的硬件编码包括Nvidia GPU与Intel QSV两种，还有一些嵌入式平台如树莓派，瑞芯微等。
首先理解一下概念，Nvidia中文名英伟达是一个厂商名字，GPU则是这个厂商生产的显卡里的一个个图像处理的逻辑单元，它主要是作图片处理，但有逻辑处理的能力，所以可以替cpu分担一些逻辑处理压力。
了解一下ffmpeg对Nvidia的GPU编码支持哪些参数，可以通过
ffmpeg -h encoder=h264_nvenc
可以看到编码的参数与x264相比有些类似，但少很多，不过关键的都在。
解码时ffmpeg对它的参数支持查看：
ffmpeg -h decoder=h264_cuvid
其中同时可以看到编码支持的像素格式包括：
Supported pixel formats: yuv420p nv12 p010le yuv444p p016le
yuv444p16le bgr0 rgb0 cuda
解码支持的像素格式很少：
Supported pixel formats: cuda nv12 p010le
举一个硬件编解码的例子：
ffmpeg -hwaccel cuvid -vcodec h264_cuvid -i input.mp4 -vf scale_npp=1920:1080 -vcodec h264_nvenc -acodec copy -f mp4 -y output.mp4
解码支持的参数：
Decoder h264_cuvid [Nvidia CUVID H264 decoder]: General capabilities: delay avoidprobe hardware Threading capabilities: none Supported hardware devices: cuda Supported pixel formats: cuda nv12 p010le p016le h264_cuvid AVOptions: -deint <int> .D.V...... Set deinterlacing mode (from 0 to 2) (default weave) weave 0 .D.V...... Weave deinterlacing (do nothing) bob 1 .D.V...... Bob deinterlacing adaptive 2 .D.V...... Adaptive deinterlacing -gpu <string> .D.V...... GPU to be used for decoding -surfaces <int> .D.V...... Maximum surfaces to be used for decoding (from 0 to INT_MAX) (default 25) -drop_second_field <boolean> .D.V...... Drop second field when deinterlacing (default false) -crop <string> .D.V...... Crop (top)x(bottom)x(left)x(right) -resize <string> .D.V...... Resize (width)x(height)
编码支持的参数：
Encoder h264_nvenc [NVIDIA NVENC H.264 encoder]: General capabilities: delay hardware Threading capabilities: none Supported hardware devices: cuda cuda Supported pixel formats: yuv420p nv12 p010le yuv444p p016le yuv444p16le bgr0 rgb0 cuda h264_nvenc AVOptions: -preset <int> E..V...... Set the encoding preset (from 0 to 11) (default medium) default 0 E..V...... slow 1 E..V...... hq 2 passes medium 2 E..V...... hq 1 pass fast 3 E..V...... hp 1 pass hp 4 E..V...... hq 5 E..V...... bd 6 E..V...... ll 7 E..V...... low latency llhq 8 E..V...... low latency hq llhp 9 E..V...... low latency hp lossless 10 E..V...... losslesshp 11 E..V...... -profile <int> E..V...... Set the encoding profile (from 0 to 3) (default main) baseline 0 E..V...... main 1 E..V...... high 2 E..V...... high444p 3 E..V...... -level <int> E..V...... Set the encoding level restriction (from 0 to 51) (default auto) auto 0 E..V...... 1 10 E..V...... 1.0 10 E..V...... 1b 9 E..V...... 1.0b 9 E..V...... 1.1 11 E..V...... 1.2 12 E..V...... 1.3 13 E..V...... 2 20 E..V...... 2.0 20 E..V...... 2.1 21 E..V...... 2.2 22 E..V...... 3 30 E..V...... 3.0 30 E..V...... 3.1 31 E..V...... 3.2 32 E..V...... 4 40 E..V...... 4.0 40 E..V...... 4.1 41 E..V...... 4.2 42 E..V...... 5 50 E..V...... 5.0 50 E..V...... 5.1 51 E..V...... -rc <int> E..V...... Override the preset rate-control (from -1 to INT_MAX) (default -1) constqp 0 E..V...... Constant QP mode vbr 1 E..V...... Variable bitrate mode cbr 2 E..V...... Constant bitrate mode vbr_minqp 8388612 E..V...... Variable bitrate mode with MinQP (deprecated) ll_2pass_quality 8388616 E..V...... Multi-pass optimized for image quality (deprecated) ll_2pass_size 8388624 E..V...... Multi-pass optimized for constant frame size (deprecated) vbr_2pass 8388640 E..V...... Multi-pass variable bitrate mode (deprecated) cbr_ld_hq 8 E..V...... Constant bitrate low delay high quality mode cbr_hq 16 E..V...... Constant bitrate high quality mode vbr_hq 32 E..V...... Variable bitrate high quality mode -rc-lookahead <int> E..V...... Number of frames to look ahead for rate-control (from 0 to INT_MAX) (default 0) -surfaces <int> E..V...... Number of concurrent surfaces (from 0 to 64) (default 0) -cbr <boolean> E..V...... Use cbr encoding mode (default false) -2pass <boolean> E..V...... Use 2pass encoding mode (default auto) -gpu <int> E..V...... Selects which NVENC capable GPU to use. First GPU is 0, second is 1, and so on. (from -2 to INT_MAX) (default any) any -1 E..V...... Pick the first device available list -2 E..V...... List the available devices -delay <int> E..V...... Delay frame output by the given amount of frames (from 0 to INT_MAX) (default INT_MAX) -no-scenecut <boolean> E..V...... When lookahead is enabled, set this to 1 to disable adaptive I-frame insertion at scene cuts (default false) -forced-idr <boolean> E..V...... If forcing keyframes, force them as IDR frames. (default false) -b_adapt <boolean> E..V...... When lookahead is enabled, set this to 0 to disable adaptive B-frame decision (default true) -spatial-aq <boolean> E..V...... set to 1 to enable Spatial AQ (default false) -spatial_aq <boolean> E..V...... set to 1 to enable Spatial AQ (default false) -temporal-aq <boolean> E..V...... set to 1 to enable Temporal AQ (default false) -temporal_aq <boolean> E..V...... set to 1 to enable Temporal AQ (default false) -zerolatency <boolean> E..V...... Set 1 to indicate zero latency operation (no reordering delay) (default false) -nonref_p <boolean> E..V...... Set this to 1 to enable automatic insertion of non-reference P-frames (default false) -strict_gop <boolean> E..V...... Set 1 to minimize GOP-to-GOP rate fluctuations (default false) -aq-strength <int> E..V...... When Spatial AQ is enabled, this field is used to specify AQ strength. AQ strength scale is from 1 (low) - 15 (aggressive) (from 1 to 15) (default 8) -cq <float> E..V...... Set target quality level (0 to 51, 0 means automatic) for constant quality mode in VBR rate control (from 0 to 51) (default 0) -aud <boolean> E..V...... Use access unit delimiters (default false) -bluray-compat <boolean> E..V...... Bluray compatibility workarounds (default false) -init_qpP <int> E..V...... Initial QP value for P frame (from -1 to 51) (default -1) -init_qpB <int> E..V...... Initial QP value for B frame (from -1 to 51) (default -1) -init_qpI <int> E..V...... Initial QP value for I frame (from -1 to 51) (default -1) -qp <int> E..V...... Constant quantization parameter rate control method (from -1 to 51) (default -1) -weighted_pred <int> E..V...... Set 1 to enable weighted prediction (from 0 to 1) (default 0) -coder <int> E..V...... Coder type (from -1 to 2) (default default) default -1 E..V...... auto 0 E..V...... cabac 1 E..V...... cavlc 2 E..V...... ac 1 E..V...... vlc 2 E..V...... -b_ref_mode <int> E..V...... Use B frames as references (from 0 to 2) (default disabled) disabled 0 E..V...... B frames will not be used for reference each 1 E..V...... Each B frame will be used for reference middle 2 E..V...... Only (number of B frames)/2 will be used for reference -a53cc <boolean> E..V...... Use A53 Closed Captions (if available) (default true) -dpb_size <int> E..V...... Specifies the DPB size used for encoding (0 means automatic) (from 0 to INT_MAX) (default 0)
