Re: [FFmpeg-devel] [PATCH 31/92] Vulkan patchset part 1 - common code changes

From: Lynne <dev@lynne.ee>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 31/92] Vulkan patchset part 1 - common code changes
Date: Wed, 19 Apr 2023 16:47:11 +0200 (CEST)
Message-ID: <NTOyxSn--3-9@lynne.ee> (raw)
In-Reply-To: <168172242060.3843.13556775994320990575@lain.khirnov.net>

Apr 17, 2023, 11:07 by anton@khirnov.net:

> Quoting Anton Khirnov (2023-04-16 22:38:16)
>
>> Quoting Lynne (2023-03-14 07:33:43)
>> > From 61f412eea3fbcb1e2a8625796760c0e24fa3fb83 Mon Sep 17 00:00:00 2001
>> > From: Lynne <dev@lynne.ee>
>> > Date: Tue, 17 Jan 2023 05:01:45 +0100
>> > Subject: [PATCH 27/92] h264dec: add hwaccel_params_buf
>> > 
>> > diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
>> > index 0aee724c0d..6559593195 100644
>> > --- a/libavcodec/h264dec.c
>> > +++ b/libavcodec/h264dec.c
>> > @@ -341,6 +341,7 @@ static av_cold int h264_decode_end(AVCodecContext *avctx)
>> >      H264Context *h = avctx->priv_data;
>> >      int i;
>> > 
>> > +    av_buffer_unref(&h->hwaccel_params_buf);
>> >      ff_h264_remove_all_refs(h);
>> >      ff_h264_free_tables(h);
>> > 
>> > @@ -470,6 +471,7 @@ static void h264_decode_flush(AVCodecContext *avctx)
>> > 
>> >      ff_h264_flush_change(h);
>> >      ff_h264_sei_uninit(&h->sei);
>> > +    av_buffer_unref(&h->hwaccel_params_buf);
>> > 
>> >      for (i = 0; i < H264_MAX_PICTURE_COUNT; i++)
>> >          ff_h264_unref_picture(h, &h->DPB[i]);
>> > @@ -669,6 +671,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
>> >              avpriv_request_sample(avctx, "data partitioning");
>> >              break;
>> >          case H264_NAL_SEI:
>> > +            av_buffer_unref(&h->hwaccel_params_buf);
>> >              if (h->setup_finished) {
>> >                  avpriv_request_sample(avctx, "Late SEI");
>> >                  break;
>> > @@ -682,6 +685,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
>> >              break;
>> >          case H264_NAL_SPS: {
>> >              GetBitContext tmp_gb = nal->gb;
>> > +            av_buffer_unref(&h->hwaccel_params_buf);
>> >              if (avctx->hwaccel && avctx->hwaccel->decode_params) {
>> >                  ret = avctx->hwaccel->decode_params(avctx,
>> >                                                      nal->type,
>>
>> Removed on SEI and SPS? That seems bizarre and highly arbitrary. Why
>> specifically those two?
>>
>
> Found the explanation in the cover letter - I assume SEI is a mistake
> and should really be PPS. The points where it is reset still seem highly
> Vulkan-specific, so I think it'd be better for the decoder to set a flag
> on seeing new parameter sets. Vulkan could would then check and clear
> the flag as needed.
>

It was a typo, changed to remove it on SPS and PPS.
We still have to store the compiled bufferref somewhere, and synchronize
it between frames, and having it in the frame context itself solves
those issues.
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