Changes between Version 33 and Version 34 of HWAccelIntro


Ignore:
Timestamp:
May 17, 2016, 8:57:34 PM (10 years ago)
Author:
llogan
Comment:

add toc. general cleanups. nvenc does not use -crf

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  • HWAccelIntro

    v33 v34  
     1[[PageOutline(2, Contents)]]
     2
    13FFmpeg provides a subsystem for hardware acceleration.
    24
    … …  
    5355† Actually yes, but is deprecated and should not be used.
    5456
    55 == VDPAU (Video Decode and Presentation API for Unix) ==
     57== VDPAU ==
     58[http://http.download.nvidia.com/XFree86/vdpau/doxygen/html/index.html Video Decode and Presentation API for Unix]. Developed by NVidia for UNIX/Linux systems. To enable this you typically need the libvdpau development package in your distribution, and a compatible graphic card.
    5659
    57 Developed by NVidia for UNIX/Linux systems. To enable this you typically need the libvdpau development package in your distribution, and a compatible graphic card.
    58 
    59 Official website:
    60 http://http.download.nvidia.com/XFree86/vdpau/doxygen/html/index.html
    61 
    62 Note that VDPAU cannot be used to decode frames in memory, the compressed frames are sent by libavcodec to the GPU device supported by VDPAU and then the decoded image can be accessed using the VDPAU API. This is not done automatically by FFmpeg, but must be done at the application level (check for example the ffmpeg_vdpau.c file used by ffmpeg.c). Also note that with this API it is not possible to move the decoded frame back to RAM, for example in case you need to encode again the decoded frame (e.g. when doing transcoding on a server).
     60Note that VDPAU cannot be used to decode frames in memory, the compressed frames are sent by libavcodec to the GPU device supported by VDPAU and then the decoded image can be accessed using the VDPAU API. This is not done automatically by FFmpeg, but must be done at the application level (check for example the {{{ffmpeg_vdpau.c}}} file used by {{{ffmpeg.c}}}). Also, note that with this API it is not possible to move the decoded frame back to RAM, for example in case you need to encode again the decoded frame (e.g. when doing transcoding on a server).
    6361
    6462Several decoders are currently supported through VDPAU in libavcodec, in particular MPEG Video, VC-1, H.264, MPEG4.
    … …  
    114112== NVENC ==
    115113
    116 NVENC is an API developed by NVIDIA which enables the use of NVIDIA GPU cards to perform H.264 and HEVC encoding. FFmpeg supports NVENC through the {{{nvenc_h264}}} and {{{nvenc_hevc}}} encoders. In order to enable it in FFmpeg you need to locally install the {{{nvEncodeAPI.h}}} headers from the NVENC SDK and configure with {{{--enable-nvenc}}}.
     114NVENC is an API developed by NVIDIA which enables the use of NVIDIA GPU cards to perform H.264 and HEVC encoding. FFmpeg supports NVENC through the {{{nvenc_h264}}} and {{{nvenc_hevc}}} encoders. In order to enable it in FFmpeg you need:
    117115
    118 To read more about the supported GPUs and download the NVENC SDK go to the following link:
    119 https://developer.nvidia.com/nvidia-video-codec-sdk
     116* A supported GPU
     117* Supported drivers
     118* Locally installed {{{nvEncodeAPI.h}}} header files from the NVENC SDK
     119* {{{ffmpeg}}} configured with {{{--enable-nvenc}}}
     120
     121Visit [https://developer.nvidia.com/nvidia-video-codec-sdk NVIDIA Video Codec SDK] to download the SDK and to read more about the supported GPUs and supported drivers.
    120122
    121123Usage example:
    122124{{{
    123 ffmpeg -i input -c:v nvenc -r 30 -profile high444p -pixel_format yuv444p -preset default  -crf 30 -b:a 128k output
     125ffmpeg -i input -c:v nvenc_h264 -profile high444p -pixel_format yuv444p -preset default output.mp4
    124126}}}
    125127
    126 you can see available presets with “-preset help”
    127 
    128 Other [https://github.com/FFmpeg/FFmpeg/blob/079b5d4ef888bd42bf0147a6d964b8bc9ec0f3c5/libavcodec/nvenc.c#L1480 options] appear to be level, tier, cbr, 2pass, buffer_delay
     128You can see available presets, other options, and encoder info with {{{ffmpeg -h encoder=nvenc_h264}}} or {{{ffmpeg -h encoder=nvenc_hevc}}}.
    129129
    130130{{{
    131 hq = high quality
    132 hp = high performance
    133 bd = Bluray Disk
    134 ll = low latency
    135 llhq = low latency high quality
    136 llhp = low latency high performance
    137 default = between llhq and llhp (same as ll?)
     131#!div style="border: 1pt dotted; margin: 1em; background-color: #fffff9;"
     132'''Note:''' If you get the {{{No NVENC capable devices found}}} error make sure you're encoding to a supported pixel format. See encoder info as shown above.
    138133}}}
    139134