Re: [FFmpeg-devel] [PATCH v2 3/3] avcodec/hevc: Add alpha layer support

Re: [FFmpeg-devel] [PATCH v2 3/3] avcodec/hevc: Add alpha layer support

[James Almer]

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On 12/15/2024 3:39 AM, Zhao Zhili wrote:
> From: Zhao Zhili <zhilizhao@tencent.com>
> 
> ---
>   libavcodec/hevc/hevcdec.c | 72 ++++++++++++++++++++++++++++++++++++++-
>   libavcodec/hevc/hevcdec.h |  2 ++
>   libavcodec/hevc/refs.c    | 10 +++++-
>   3 files changed, 82 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/hevc/hevcdec.c b/libavcodec/hevc/hevcdec.c
> index be35a9de82..3675ac1e2b 100644
> --- a/libavcodec/hevc/hevcdec.c
> +++ b/libavcodec/hevc/hevcdec.c
> @@ -458,6 +458,24 @@ static int export_multilayer(HEVCContext *s, const HEVCVPS *vps)
>       return 0;
>   }
>   
> +int ff_hevc_is_alpha_video(const HEVCContext *s) {
> +    const HEVCVPS *vps = s->vps;
> +    int ret = 0;
> +
> +    if (vps->nb_layers != 2 || !vps->layer_id_in_nuh[1])
> +        return 0;
> +
> +    /* decode_vps_ext() guarantees that SCALABILITY_AUXILIARY with AuxId other
> +     * than alpha cannot reach here.
> +     */
> +    ret = (s->vps->scalability_mask_flag & HEVC_SCALABILITY_AUXILIARY);
> +
> +    av_log(s->avctx, AV_LOG_DEBUG, "Multi layer video, %s alpha video\n",
> +           ret ? "is" : "not");
> +
> +    return ret;
> +}
> +
>   static int setup_multilayer(HEVCContext *s, const HEVCVPS *vps)
>   {
>       unsigned layers_active_output = 0, highest_layer;
> @@ -465,6 +483,18 @@ static int setup_multilayer(HEVCContext *s, const HEVCVPS *vps)
>       s->layers_active_output = 1;
>       s->layers_active_decode = 1;
>   
> +    if (ff_hevc_is_alpha_video(s)) {
> +        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
> +
> +        if (!(desc->flags & AV_PIX_FMT_FLAG_ALPHA))
> +            return 0;
> +
> +        s->layers_active_decode = (1 << vps->nb_layers) - 1;
> +        s->layers_active_output = 1;
> +
> +        return 0;
> +    }
> +
>       // nothing requested - decode base layer only
>       if (!s->nb_view_ids)
>           return 0;
> @@ -522,6 +552,34 @@ static int setup_multilayer(HEVCContext *s, const HEVCVPS *vps)
>       return 0;
>   }
>   
> +static enum AVPixelFormat map_to_alpha_format(HEVCContext *s,
> +                                              enum AVPixelFormat pix_fmt)
> +{
> +    switch (pix_fmt) {
> +    case AV_PIX_FMT_YUV420P:
> +    case AV_PIX_FMT_YUVJ420P:
> +        return AV_PIX_FMT_YUVA420P;
> +    case AV_PIX_FMT_YUV420P10:
> +        return AV_PIX_FMT_YUVA420P10;
> +    case AV_PIX_FMT_YUV444P:
> +        return AV_PIX_FMT_YUVA444P;
> +    case AV_PIX_FMT_YUV422P:
> +        return AV_PIX_FMT_YUVA422P;
> +    case AV_PIX_FMT_YUV422P10LE:
> +        return AV_PIX_FMT_YUVA422P10LE;
> +    case AV_PIX_FMT_YUV444P10:
> +        return AV_PIX_FMT_YUVA444P10;
> +    case AV_PIX_FMT_YUV444P12:
> +        return AV_PIX_FMT_YUVA444P12;
> +    case AV_PIX_FMT_YUV422P12:
> +        return AV_PIX_FMT_YUVA422P12;
> +    default:
> +        av_log(s->avctx, AV_LOG_WARNING, "No alpha pixel format map for %s\n",
> +               av_get_pix_fmt_name(pix_fmt));
> +        return AV_PIX_FMT_NONE;
> +    }
> +}
> +
>   static enum AVPixelFormat get_format(HEVCContext *s, const HEVCSPS *sps)
>   {
>   #define HWACCEL_MAX (CONFIG_HEVC_DXVA2_HWACCEL + \
> @@ -532,9 +590,13 @@ static enum AVPixelFormat get_format(HEVCContext *s, const HEVCSPS *sps)
>                        CONFIG_HEVC_VIDEOTOOLBOX_HWACCEL + \
>                        CONFIG_HEVC_VDPAU_HWACCEL + \
>                        CONFIG_HEVC_VULKAN_HWACCEL)
> -    enum AVPixelFormat pix_fmts[HWACCEL_MAX + 2], *fmt = pix_fmts;
> +    enum AVPixelFormat pix_fmts[HWACCEL_MAX + 3], *fmt = pix_fmts;
> +    enum AVPixelFormat alpha_fmt = AV_PIX_FMT_NONE;
>       int ret;
>   
> +    if (ff_hevc_is_alpha_video(s))
> +        alpha_fmt = map_to_alpha_format(s, sps->pix_fmt);
> +
>       switch (sps->pix_fmt) {
>       case AV_PIX_FMT_YUV420P:
>       case AV_PIX_FMT_YUVJ420P:
> @@ -650,6 +712,8 @@ static enum AVPixelFormat get_format(HEVCContext *s, const HEVCSPS *sps)
>           break;
>       }
>   
> +    if (alpha_fmt != AV_PIX_FMT_NONE)
> +        *fmt++ = alpha_fmt;
>       *fmt++ = sps->pix_fmt;
>       *fmt = AV_PIX_FMT_NONE;
>   
> @@ -3182,6 +3246,12 @@ static int hevc_frame_start(HEVCContext *s, HEVCLayerContext *l,
>                   !sps->vui.common.video_signal_type_present_flag)
>                   pix_fmt = sps_base->pix_fmt;
>   
> +            // Ignore range mismatch between base layer and alpha layer
> +            if (ff_hevc_is_alpha_video(s) &&
> +                sps_base->pix_fmt == AV_PIX_FMT_YUV420P &&
> +                pix_fmt == AV_PIX_FMT_YUVJ420P)
> +                pix_fmt = sps_base->pix_fmt;
> +
>               if (pix_fmt     != sps_base->pix_fmt ||
>                   sps->width  != sps_base->width   ||
>                   sps->height != sps_base->height) {
> diff --git a/libavcodec/hevc/hevcdec.h b/libavcodec/hevc/hevcdec.h
> index 473709b4e8..f8ed156a1c 100644
> --- a/libavcodec/hevc/hevcdec.h
> +++ b/libavcodec/hevc/hevcdec.h
> @@ -714,6 +714,8 @@ void ff_hevc_hls_residual_coding(HEVCLocalContext *lc, const HEVCPPS *pps,
>   
>   void ff_hevc_hls_mvd_coding(HEVCLocalContext *lc, int x0, int y0, int log2_cb_size);
>   
> +int ff_hevc_is_alpha_video(const HEVCContext *s);
> +
>   extern const uint8_t ff_hevc_qpel_extra_before[4];
>   extern const uint8_t ff_hevc_qpel_extra_after[4];
>   extern const uint8_t ff_hevc_qpel_extra[4];
> diff --git a/libavcodec/hevc/refs.c b/libavcodec/hevc/refs.c
> index 6ba667e9f5..93cef509fa 100644
> --- a/libavcodec/hevc/refs.c
> +++ b/libavcodec/hevc/refs.c
> @@ -103,7 +103,7 @@ static HEVCFrame *alloc_frame(HEVCContext *s, HEVCLayerContext *l)
>           }
>   
>           // add view ID side data if it's nontrivial
> -        if (vps->nb_layers > 1 || view_id) {
> +        if (!ff_hevc_is_alpha_video(s) && (vps->nb_layers > 1 || view_id)) {
>               HEVCSEITDRDI *tdrdi = &s->sei.tdrdi;
>               AVFrameSideData *sd = av_frame_side_data_new(&frame->f->side_data,
>                                                            &frame->f->nb_side_data,
> @@ -162,6 +162,14 @@ static HEVCFrame *alloc_frame(HEVCContext *s, HEVCLayerContext *l)
>               goto fail;
>   
>           frame->pps = ff_refstruct_ref_c(s->pps);

Could you please send a rebased patchset? It doesn't apply cleanly 
anymore because of changes, like in this line.

> +        if (l != &s->layers[0] && ff_hevc_is_alpha_video(s)) {
> +            AVFrame *alpha = frame->f;
> +            AVFrame *base = s->layers[0].cur_frame->f;
> +
> +            av_buffer_replace(&alpha->buf[0], base->buf[3]);
> +            alpha->linesize[0] = base->linesize[3];
> +            alpha->data[0] = base->data[3];
> +        }
>   
>           return frame;
>   fail:


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