[FFmpeg-devel] [PATCH] lavc/vaapi_encode_h265: add support for low-power encoding

[Mark Thompson]

On 09/02/18 01:23, Xiang, Haihao wrote:
> 
>> On 06/02/18 08:17, Haihao Xiang wrote:
>>> Although VAEntrypointEncSliceLP was added in old version of VAAPI, we
>>> never implemented it for VAAPI H265 encoder before. so it is reasonable
>>> to require VAAPI 1.0
>>>
>>> Signed-off-by: Haihao Xiang <haihao.xiang at intel.com>
>>> ---
>>>  libavcodec/vaapi_encode_h265.c | 18 +++++++++++++++++-
>>>  1 file changed, 17 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/libavcodec/vaapi_encode_h265.c b/libavcodec/vaapi_encode_h265.c
>>> index f3b4f6c7e26..efe1148127f 100644
>>> --- a/libavcodec/vaapi_encode_h265.c
>>> +++ b/libavcodec/vaapi_encode_h265.c
>>> @@ -65,6 +65,7 @@ typedef struct VAAPIEncodeH265Options {
>>>      int aud;
>>>      int profile;
>>>      int level;
>>> +    int low_power;
>>>  } VAAPIEncodeH265Options;
>>>  
>>>  
>>> @@ -914,7 +915,18 @@ static av_cold int
>>> vaapi_encode_h265_init(AVCodecContext *avctx)
>>>                 avctx->profile);
>>>          return AVERROR(EINVAL);
>>>      }
>>> -    ctx->va_entrypoint = VAEntrypointEncSlice;
>>> +
>>> +    if (opt->low_power) {
>>> +#if VA_CHECK_VERSION(1, 0, 0)
>>> +        ctx->va_entrypoint = VAEntrypointEncSliceLP;
>>> +#else
>>> +        av_log(avctx, AV_LOG_ERROR, "Low-power encoding is not "
>>> +               "supported with this VAAPI version.\n");
>>> +        return AVERROR(EINVAL);
>>> +#endif
>>> +    } else {
>>> +        ctx->va_entrypoint = VAEntrypointEncSlice;
>>> +    }
>>>  
>>>      if (avctx->bit_rate > 0) {
>>>          if (avctx->rc_max_rate == avctx->bit_rate)
>>> @@ -986,6 +998,10 @@ static const AVOption vaapi_encode_h265_options[] = {
>>>      { LEVEL("6.2", 186) },
>>>  #undef LEVEL
>>>  
>>> +    { "low_power", "Use low-power encoding mode (experimental: only
>>> supported "
>>
>> Do you want to copy this comment?
>>
> 
> Actually I want to delete the comments in (), but the limitation for HEVC low
> power encoding still exist. It would be better to add some VAAPI attributes to
> query the capability/limitation etc.
> 
> 
>>> +      "on some platforms, does not support all features)",
>>> +      OFFSET(low_power), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, FLAGS },
>>> +
>>>      { NULL },
>>>  };
>>>  
>>>
>>
>> How can I test this (and the following patch)?  It doesn't appear to exist on
>> any current platform/driver.
>>
> 
> Cannon Lake support HEVC low power encoding, do you have this platform?  https:/
> /github.com/intel/media-driver/ should support this feature but it isn't ready
> in https://github.com/intel/intel-vaapi-driver. 

I do not have any board with this - where can I get one?

>> I don't like how this code is being copied around, but I guess it would work
>> for now.  I'll look into doing something more sensible here.
>>
> 
> I also dislike duplicated code. I wanted to add some common options for VAAPI
> encoder in FFmpeg, such as QP. However low power encoding is not available for
> some codecs, such as VP8, so I copied&pasted the code here. 
> 
> Another thing is a driver may not support both VAEntrypointEncSliceLP and
> VAEntrypointEncSlice, so I want to change the value range of low_power to -1, 0,
> 1. -1 means auto mode, FFmpeg-vaapi will select the first applicable entrypoint,
> what is your comment for this proposal?

Under what circumstances would a driver a provide low-power entrypoint but not a standard one?  If some hardware only supports one encoder I would expect it to regard that encoder as the standard one.

- Mark