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avcodec/amfenc: make encoder statistics feedback opt-in

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Commit 87b7e578ec ("avcodec/amfenc: add encoder average QP stats") enables
AMF_VIDEO_ENCODER_*_STATISTICS_FEEDBACK on every submitted surface. The AMF
property defaults to false and asking the encoder to collect per-frame
statistics is not free: the hardware has to gather the average QP over all
CTBs of every picture.

On a Radeon RX 9070 XT (Navi48, VCN5) driven through the open source
Mesa/RADV Vulkan backend the cost is roughly 48% additional wall time per
frame, for a bit identical bitstream. Measured with a minimal build
(--enable-amf, AMF headers v1.5.2), 1080p23.976, 4353 frames, hevc_amf,
-rc cqp -qp_i 24 -qp_p 24, software decode. Median of repeated runs on an
otherwise idle machine:

  n8.1.2                     -quality speed      9.27 s   469.6 fps
  n9.0.1                     -quality speed     13.78 s   315.9 fps
  n9.0.1 + this patch        -quality speed      9.27 s   469.6 fps
  n9.0.1 + this patch, -qp_stats 1              13.78 s   315.9 fps

  n8.1.2                     -quality quality   16.29 s   267.2 fps
  n9.0.1                     -quality quality   24.05 s   181.0 fps
  n9.0.1 + this patch        -quality quality   16.29 s   267.2 fps
  n9.0.1 + this patch, -qp_stats 1              23.80 s   182.9 fps

The SHA256 of the encoded video stream is identical across all runs, with
and without the feedback enabled. Per-process DRM fdinfo shows the VCN
encode engine going from 69% to 92% busy at the quality preset once the
feedback is disabled - the engine was being starved, not doing more work.

Other encoders that call ff_encode_add_stats_side_data() (libx264, libx265,
libsvtav1, ...) get the quantiser for free from data they already have, so
reporting it unconditionally costs them nothing. That is not the case here,
which is why this is made opt-in rather than always on.

Add a qp_stats AVOption, defaulting to false, restoring pre-9.0 throughput
by default. Users who want the average QP reported in the ffmpeg CLI
progress line, or as AV_PKT_DATA_QUALITY_STATS side data, can enable it
with -qp_stats 1.
This commit is contained in:
Marcin Krycki
2026-09-06 14:36:27 +01:00
committed by michaelni
parent e31413fb96
commit bed45b6f2f
5 changed files with 14 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
libavcodec/amfenc.c
View File

@@ -250,7 +250,7 @@ static int amf_copy_buffer(AVCodecContext *avctx, AVPacket *pkt, AMFBuffer *buff
break;
}
if (average_qp >= 0) {
if (ctx->qp_stats && average_qp >= 0) {
ff_encode_add_stats_side_data(pkt, average_qp * FF_QP2LAMBDA, NULL, 0, pict_type);
}
@@ -475,7 +475,9 @@ static int amf_submit_frame(AVCodecContext *avctx, AVFrame *frame, AMFSurface
switch (avctx->codec->id) {
case AV_CODEC_ID_H264:
AMF_ASSIGN_PROPERTY_BOOL(res, surface, AMF_VIDEO_ENCODER_STATISTICS_FEEDBACK, 1);
if (ctx->qp_stats) {
AMF_ASSIGN_PROPERTY_BOOL(res, surface, AMF_VIDEO_ENCODER_STATISTICS_FEEDBACK, 1);
}
AMF_ASSIGN_PROPERTY_INT64(res, surface, AMF_VIDEO_ENCODER_INSERT_AUD, !!ctx->aud);
switch (frame->pict_type) {
case AV_PICTURE_TYPE_I:
@@ -496,7 +498,9 @@ static int amf_submit_frame(AVCodecContext *avctx, AVFrame *frame, AMFSurface
}
break;
case AV_CODEC_ID_HEVC:
AMF_ASSIGN_PROPERTY_BOOL(res, surface, AMF_VIDEO_ENCODER_HEVC_STATISTICS_FEEDBACK, 1);
if (ctx->qp_stats) {
AMF_ASSIGN_PROPERTY_BOOL(res, surface, AMF_VIDEO_ENCODER_HEVC_STATISTICS_FEEDBACK, 1);
}
AMF_ASSIGN_PROPERTY_INT64(res, surface, AMF_VIDEO_ENCODER_HEVC_INSERT_AUD, !!ctx->aud);
switch (frame->pict_type) {
case AV_PICTURE_TYPE_I:
@@ -513,7 +517,9 @@ static int amf_submit_frame(AVCodecContext *avctx, AVFrame *frame, AMFSurface
}
break;
case AV_CODEC_ID_AV1:
AMF_ASSIGN_PROPERTY_BOOL(res, surface, AMF_VIDEO_ENCODER_AV1_STATISTICS_FEEDBACK, 1);
if (ctx->qp_stats) {
AMF_ASSIGN_PROPERTY_BOOL(res, surface, AMF_VIDEO_ENCODER_AV1_STATISTICS_FEEDBACK, 1);
}
if (frame->pict_type == AV_PICTURE_TYPE_I) {
if (ctx->forced_idr) {
AMF_ASSIGN_PROPERTY_INT64(res, surface, AMF_VIDEO_ENCODER_AV1_FORCE_INSERT_SEQUENCE_HEADER, 1);

1
libavcodec/amfenc.h
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@@ -100,6 +100,7 @@ typedef struct AMFEncoderContext {
int qvbr_quality_level;
int hw_high_motion_quality_boost;
int forced_idr;
int qp_stats;
// HEVC - specific options

1
libavcodec/amfenc_av1.c
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@@ -130,6 +130,7 @@ static const AVOption options[] = {
{ "caq", "context adaptive quantization", 0, AV_OPT_TYPE_CONST, {.i64 = AMF_VIDEO_ENCODER_AV1_AQ_MODE_CAQ }, 0, 0, VE, .unit = "adaptive_quantisation_mode" },
{ "forced_idr", "Force I frames to be IDR frames", OFFSET(forced_idr), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
{ "qp_stats", "Report average QP per frame as packet side data (reduces throughput)", OFFSET(qp_stats), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
{ "align", "alignment mode", OFFSET(align), AV_OPT_TYPE_INT, {.i64 = AMF_VIDEO_ENCODER_AV1_ALIGNMENT_MODE_NO_RESTRICTIONS }, AMF_VIDEO_ENCODER_AV1_ALIGNMENT_MODE_64X16_ONLY, AMF_VIDEO_ENCODER_AV1_ALIGNMENT_MODE_NO_RESTRICTIONS, VE, .unit = "align" },
{ "64x16", "", 0, AV_OPT_TYPE_CONST, {.i64 = AMF_VIDEO_ENCODER_AV1_ALIGNMENT_MODE_64X16_ONLY }, 0, 0, VE, .unit = "align" },

1
libavcodec/amfenc_h264.c
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@@ -140,6 +140,7 @@ static const AVOption options[] = {
{ "me_quarter_pel", "Enable ME Quarter Pixel", OFFSET(me_quarter_pel),AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, VE },
{ "forced_idr", "Force I frames to be IDR frames", OFFSET(forced_idr) , AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
{ "qp_stats", "Report average QP per frame as packet side data (reduces throughput)", OFFSET(qp_stats), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
{ "aud", "Inserts AU Delimiter NAL unit", OFFSET(aud) , AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, VE },
{ "smart_access_video", "Enable Smart Access Video to enhance performance by utilizing both APU and dGPU memory access", OFFSET(smart_access_video), AV_OPT_TYPE_BOOL, {.i64 = -1 }, -1, 1, VE},

1
libavcodec/amfenc_hevc.c
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@@ -111,6 +111,7 @@ static const AVOption options[] = {
{ "me_quarter_pel", "Enable ME Quarter Pixel ", OFFSET(me_quarter_pel),AV_OPT_TYPE_BOOL,{ .i64 = -1 }, -1, 1, VE },
{ "forced_idr", "Force I frames to be IDR frames", OFFSET(forced_idr) ,AV_OPT_TYPE_BOOL,{ .i64 = 0 }, 0, 1, VE },
{ "qp_stats", "Report average QP per frame as packet side data (reduces throughput)", OFFSET(qp_stats), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
{ "aud", "Inserts AU Delimiter NAL unit", OFFSET(aud) ,AV_OPT_TYPE_BOOL,{ .i64 = -1 }, -1, 1, VE },
{ "smart_access_video", "Enable Smart Access Video to enhance performance by utilizing both APU and dGPU memory access", OFFSET(smart_access_video), AV_OPT_TYPE_BOOL, {.i64 = -1 }, -1, 1, VE},