[FFmpeg-devel] [PATCH v6 3/3] avcodec/hevc: Add alpha layer support
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Tue Feb 11 15:02:30 EET 2025
Zhao Zhili:
>
>
>> On Feb 11, 2025, at 20:12, Andreas Rheinhardt <andreas.rheinhardt at outlook.com> wrote:
>>
>> Zhao Zhili:
>>>
>>>
>>>> On Feb 11, 2025, at 19:23, Andreas Rheinhardt <andreas.rheinhardt at outlook.com> wrote:
>>>>
>>>> Zhao Zhili:
>>>>> From: Zhao Zhili <zhilizhao at tencent.com>
>>>>>
>>>>> Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
>>>>> ---
>>>>> libavcodec/hevc/hevcdec.c | 73 ++++++++++++++++++++++++++++++++++++++-
>>>>> libavcodec/hevc/hevcdec.h | 2 ++
>>>>> libavcodec/hevc/refs.c | 34 +++++++++++++++++-
>>>>> 3 files changed, 107 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/libavcodec/hevc/hevcdec.c b/libavcodec/hevc/hevcdec.c
>>>>> index e9c045f7a1..f71edf213b 100644
>>>>> --- a/libavcodec/hevc/hevcdec.c
>>>>> +++ b/libavcodec/hevc/hevcdec.c
>>>>> @@ -466,6 +466,25 @@ 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;
>>>>> @@ -473,6 +492,18 @@ 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 +561,34 @@ 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 +599,13 @@ 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 +727,8 @@ 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 +3259,12 @@ 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..da0bac8d9c 100644
>>>>> --- a/libavcodec/hevc/refs.c
>>>>> +++ b/libavcodec/hevc/refs.c
>>>>> @@ -79,6 +79,30 @@ void ff_hevc_flush_dpb(HEVCContext *s)
>>>>> }
>>>>> }
>>>>>
>>>>> +static int replace_alpha_plane(AVFrame *alpha, AVFrame *base)
>>>>> +{
>>>>> + AVBufferRef *base_a = av_frame_get_plane_buffer(base, 3);
>>>>> + uint8_t *data = alpha->data[0];
>>>>> + int ret;
>>>>> +
>>>>> + for (int i = 0; i < FF_ARRAY_ELEMS(alpha->buf) && alpha->buf[i]; i++) {
>>>>> + AVBufferRef *buf = alpha->buf[i];
>>>>> +
>>>>> + if (data >= buf->data && data < buf->data + buf->size) {
>>>>
>>>> Pointer comparisons (other than equality/inquality comparisons) are
>>>> undefined behavior unless the two pointers point into the same array (or
>>>> one past the last element of an array).
>>>
>>> av_frame_get_plane_buffer does the same compare. Any idea to fix this UB?
>>
>> ISO C does not have a portable way to achieve this (except iterating
>> over buf->data[0..buf->size] and checking via ==).
>> In practice (in a flat memory space) casting to uintptr_t should work.
>
> What’s the difference with and without cast in practice?
I don't know any atm; maybe future versions of USan will warn about
invalid pointer comparisons?
>
>>
>>>
>>>>
>>>>> + ret = av_buffer_replace(&alpha->buf[i], base_a);
>>>>> + if (ret < 0)
>>>>> + return ret;
>>>>> +
>>>>> + alpha->linesize[0] = base->linesize[3];
>>>>> + alpha->data[0] = base->data[3];
>>>>> +
>>>>> + return 0;
>>>>> + }
>>>>> + }
>>>>> +
>>>>> + return AVERROR_BUG;
>>>>> +}
>>>>> +
>>>>> static HEVCFrame *alloc_frame(HEVCContext *s, HEVCLayerContext *l)
>>>>> {
>>>>> const HEVCVPS *vps = l->sps->vps;
>>>>> @@ -103,7 +127,7 @@ 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 +185,15 @@ 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;
>>>>> + ret = replace_alpha_plane(alpha, base);
>>>>> + if (ret < 0)
>>>>> + goto fail;
>>>>> + }
>>>>>
>>>>> return frame;
>>>>> fail:
>>>>
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