Re: [FFmpeg-devel] [PATCH v2] avcodec/av1_vaapi: add direct film grain mode

[Mark Thompson <sw@jkqxz.net>]

On 22/11/2022 19:18, Dong, Ruijing wrote:
> [AMD Official Use Only - General]
> 
> Hi Mark,
> 
> Sorry for being late to reply to you.
> 
> Your understanding is correct, and I have sent a new patch [v4] for addressing the current issue and to use
> driver quirk mechanism to specify only AMD VAAPI driver has this behavior, then this could be more specific.
> 
> For AMD hardware, it allocates GPU memory internally for the DPB management, the output is always the final one with or without applied film-grain.

I don't see why this requires you to write the output to the wrong surface.  Why not write it to the correct one instead?

- Mark

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of Mark Thompson
> Sent: Sunday, November 20, 2022 11:44 AM
> To: ffmpeg-devel@ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH v2] avcodec/av1_vaapi: add direct film grain mode
> 
> On 20/11/2022 02:59, Ruijing Dong wrote:
>> Adding direct film grain mode for av1 decoder, which outputs alongside
>> film grain.
>>
>> AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN is the new flag introduced to enable
>> this path.
>>
>> issue:
>> By using AMD av1 decoder via VAAPI, when used with film grain content,
>> the output displays black screen with incorrect frame order.
>>
>> The issue being discussed in here:
>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitl
>> ab.freedesktop.org%2Fmesa%2Fmesa%2F-%2Fissues%2F6903%23note_1613807&am
>> p;data=05%7C01%7Cruijing.dong%40amd.com%7C6f75be6a4f8044fe037d08dacb16
>> 8529%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638045595864762041%7
>> CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1
>> haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=Ms7PCNEjOs09JVQd2KB46St5
>> w3V8Idbc2shZC80VefI%3D&amp;reserved=0
>>
>> example:
>> This flag can be used in ffmpeg command:
>>
>> ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128
>>         -hwaccel_flags 8
>>         -i input_with_film_gram.obu
>>         output_with_film_grain.yuv
>>
>> Signed-off-by: Ruijing Dong <ruijing.dong@amd.com>
>> ---
>> update: add new option direct_film_grain in optons_table.h
>>
>>    libavcodec/avcodec.h       | 17 +++++++++++++++++
>>    libavcodec/options_table.h |  1 +
>>    libavcodec/vaapi_av1.c     |  6 ++++--
>>    3 files changed, 22 insertions(+), 2 deletions(-)
> 
> My understanding of this is as follows, please correct me if any of this is wrong:
> 
> * For AV1 with film grain enabled, VAAPI decode is specified with two output surfaces: one for pre-grain (reference) output and one for post-grain (display) output.
> * The current driver in Mesa always writes to the pre-grain surface and ignores the post-grain surface entirely.
> * To fix this, you intend to modify the VAAPI code in libavcodec to allow the user to manually override the expected VAAPI behaviour and instead assume that the post-grain output has been written to the pre-grain surface.
> 
> Is that right?
> 
> 
> [rdong]:
> 
> If it is, could you perhaps explain why this manual option is preferable to the more obvious solution of Mesa being fixed to write the post-grain output to the post-grain surface?
> 
> Thanks,
> 
> - Mark
> 
> 
>> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h index
>> 3edd8e2636..9420e7820d 100644
>> --- a/libavcodec/avcodec.h
>> +++ b/libavcodec/avcodec.h
>> @@ -2253,6 +2253,23 @@ typedef struct AVHWAccel {
>>     */
>>    #define AV_HWACCEL_FLAG_ALLOW_PROFILE_MISMATCH (1 << 2)
>>
>> +/**
>> + * The film grain synthesis could be seperate from decoding process.
>> + * The downstream device would apply the film grain parameters seperately.
>> + * The desired film grain parameters can be found in SEI section in
>> +H264
>> + * or H265 bitstreams.
>> + *
>> + * In AV1, film grain is mandatorily specified, av1 decoders like AMD
>> + * av1 decoder process film grain content internally, and the output
>> + * includes applied film grain. For the purpose of supporting these
>> +av1
>> + * decoders, this flag needs to be utilized.
>> + *
>> + * @warning If the stream has no film grain content, this flag will
>> + *          be ignored in the supported av1 decoders. It is advised
>> + *          that this flag should only be used in av1 decoders
>> + *          that support it.
>> + */
>> +#define AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN (1 << 3)
>>    /**
>>     * @}
>>     */
>> diff --git a/libavcodec/options_table.h b/libavcodec/options_table.h
>> index cd02f5096f..0302f89280 100644
>> --- a/libavcodec/options_table.h
>> +++ b/libavcodec/options_table.h
>> @@ -399,6 +399,7 @@ static const AVOption avcodec_options[] = {
>>    {"ignore_level", "ignore level even if the codec level used is unknown or higher than the maximum supported level reported by the hardware driver", 0, AV_OPT_TYPE_CONST, { .i64 = AV_HWACCEL_FLAG_IGNORE_LEVEL }, INT_MIN, INT_MAX, V | D, "hwaccel_flags" },
>>    {"allow_high_depth", "allow to output YUV pixel formats with a different chroma sampling than 4:2:0 and/or other than 8 bits per component", 0, AV_OPT_TYPE_CONST, {.i64 = AV_HWACCEL_FLAG_ALLOW_HIGH_DEPTH }, INT_MIN, INT_MAX, V | D, "hwaccel_flags"},
>>    {"allow_profile_mismatch", "attempt to decode anyway if HW
>> accelerated decoder's supported profiles do not exactly match the
>> stream", 0, AV_OPT_TYPE_CONST, {.i64 =
>> AV_HWACCEL_FLAG_ALLOW_PROFILE_MISMATCH }, INT_MIN, INT_MAX, V | D,
>> "hwaccel_flags"},
>> +{"direct_film_grain", "allow decoder to directly apply film grain to
>> +the output", 0, AV_OPT_TYPE_CONST, {.i64 =
>> +AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN }, INT_MIN, INT_MAX, V | D,
>> +"hwaccel_flags"},
>>    {"extra_hw_frames", "Number of extra hardware frames to allocate for the user", OFFSET(extra_hw_frames), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, V|D },
>>    {"discard_damaged_percentage", "Percentage of damaged samples to discard a frame", OFFSET(discard_damaged_percentage), AV_OPT_TYPE_INT, {.i64 = 95 }, 0, 100, V|D },
>>    {NULL},
>> diff --git a/libavcodec/vaapi_av1.c b/libavcodec/vaapi_av1.c index
>> d0339b2705..6db910f2bf 100644
>> --- a/libavcodec/vaapi_av1.c
>> +++ b/libavcodec/vaapi_av1.c
>> @@ -127,6 +127,7 @@ static int vaapi_av1_start_frame(AVCodecContext *avctx,
>>        int8_t bit_depth_idx;
>>        int err = 0;
>>        int apply_grain = !(avctx->export_side_data &
>> AV_CODEC_EXPORT_DATA_FILM_GRAIN) && film_grain->apply_grain;
>> +    int direct_film_grain = avctx->hwaccel_flags &
>> + AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN;
>>        uint8_t remap_lr_type[4] = {AV1_RESTORE_NONE, AV1_RESTORE_SWITCHABLE, AV1_RESTORE_WIENER, AV1_RESTORE_SGRPROJ};
>>        uint8_t segmentation_feature_signed[AV1_SEG_LVL_MAX] = {1, 1, 1, 1, 1, 0, 0, 0};
>>        uint8_t segmentation_feature_max[AV1_SEG_LVL_MAX] = {255,
>> AV1_MAX_LOOP_FILTER, @@ -136,7 +137,7 @@ static int vaapi_av1_start_frame(AVCodecContext *avctx,
>>        if (bit_depth_idx < 0)
>>            goto fail;
>>
>> -    if (apply_grain) {
>> +    if (apply_grain && !direct_film_grain) {
>>            if (ctx->tmp_frame->buf[0])
>>                ff_thread_release_buffer(avctx, ctx->tmp_frame);
>>            err = ff_thread_get_buffer(avctx, ctx->tmp_frame,
>> AV_GET_BUFFER_FLAG_REF); @@ -375,6 +376,7 @@ static int vaapi_av1_end_frame(AVCodecContext *avctx)
>>        VAAPIAV1DecContext *ctx = avctx->internal->hwaccel_priv_data;
>>
>>        int apply_grain = !(avctx->export_side_data &
>> AV_CODEC_EXPORT_DATA_FILM_GRAIN) && film_grain->apply_grain;
>> +    int direct_film_grain = avctx->hwaccel_flags &
>> + AV_HWACCEL_FLAG_DIRECT_FILM_GRAIN;
>>        int ret;
>>        ret = ff_vaapi_decode_issue(avctx, pic);
>>        if (ret < 0)
>> @@ -385,7 +387,7 @@ static int vaapi_av1_end_frame(AVCodecContext *avctx)
>>                if (ctx->ref_tab[i].frame->buf[0])
>>                    ff_thread_release_buffer(avctx,
>> ctx->ref_tab[i].frame);
>>
>> -            if (apply_grain) {
>> +            if (apply_grain && !direct_film_grain) {
>>                    ret = av_frame_ref(ctx->ref_tab[i].frame, ctx->tmp_frame);
>>                    if (ret < 0)
>>                        return ret;
>> --
>> 2.25.1
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