[FFmpeg-devel] [PATCH v5 3/3] avcodec/hevc: Add alpha layer support
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Tue Feb 11 10:16:42 EET 2025
Zhao Zhili:
> From: Zhao Zhili <zhilizhao at tencent.com>
>
> Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
> ---
> libavcodec/hevc/hevcdec.c | 72 ++++++++++++++++++++++++++++++++++++++-
> libavcodec/hevc/hevcdec.h | 2 ++
> libavcodec/hevc/refs.c | 11 +++++-
> 3 files changed, 83 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/hevc/hevcdec.c b/libavcodec/hevc/hevcdec.c
> index e9c045f7a1..1cdc28de50 100644
> --- a/libavcodec/hevc/hevcdec.c
> +++ b/libavcodec/hevc/hevcdec.c
> @@ -466,6 +466,24 @@ static int export_multilayer(HEVCContext *s, const HEVCVPS *vps)
> return 0;
> }
>
> +int ff_hevc_is_alpha_video(const HEVCContext *s) {
'{’ should be on its own line.
> + 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;
> @@ -473,6 +491,18 @@ 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;
> @@ -530,6 +560,34 @@ 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 + \
> @@ -540,9 +598,13 @@ 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:
> @@ -664,6 +726,8 @@ 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;
>
> @@ -3194,6 +3258,12 @@ 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 4e95035688..b2b725b5cd 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 dd7f7f95a8..da99f79742 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,
> @@ -161,7 +161,16 @@ static HEVCFrame *alloc_frame(HEVCContext *s, HEVCLayerContext *l)
> if (ret < 0)
> goto fail;
>
> +
> frame->pps = av_refstruct_ref_c(s->pps);
> + 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];
> + }
This code seems to presume that the AVBufferRef backing data[i] is
buf[i]. But there is no such requirement (the documentation merely
states "All pointers in data and extended_data must point into one of
the AVBufferRef in buf or extended_buf").
Apart from that: Missing check for av_buffer_replace().
>
> return frame;
> fail:
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