[FFmpeg-devel] [PATCH V2 3/3] libavcodec/vaapi_encode: Add async_depth to vaapi_encoder to increase performance

[Wenbin Chen]

Add async_depth to increase encoder's performance. Reuse encode_fifo as
async buffer. Encoder puts all reordered frame to HW and then check
fifo size. If fifo < async_depth and the top frame is not ready, it will
return AVERROR(EAGAIN) to require more frames.

1080p transcoding (no B frames) with -async_depth=4 can increase 20%
performance on my environment.
The async increases performance but also introduces frame delay.

Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
---
 libavcodec/vaapi_encode.c | 19 ++++++++++++++-----
 libavcodec/vaapi_encode.h | 12 ++++++++++--
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/libavcodec/vaapi_encode.c b/libavcodec/vaapi_encode.c
index 9a3b3ba4ad..f9ffca0475 100644
--- a/libavcodec/vaapi_encode.c
+++ b/libavcodec/vaapi_encode.c
@@ -1158,7 +1158,8 @@ static int vaapi_encode_send_frame(AVCodecContext *avctx, AVFrame *frame)
         if (ctx->input_order == ctx->decode_delay)
             ctx->dts_pts_diff = pic->pts - ctx->first_pts;
         if (ctx->output_delay > 0)
-            ctx->ts_ring[ctx->input_order % (3 * ctx->output_delay)] = pic->pts;
+            ctx->ts_ring[ctx->input_order %
+                        (3 * ctx->output_delay + ctx->async_depth)] = pic->pts;
 
         pic->display_order = ctx->input_order;
         ++ctx->input_order;
@@ -1214,8 +1215,8 @@ int ff_vaapi_encode_receive_packet(AVCodecContext *avctx, AVPacket *pkt)
 
 #if VA_CHECK_VERSION(1, 9, 0)
     if (ctx->has_sync_buffer_func) {
-        while (av_fifo_size(ctx->encode_fifo) <=
-               MAX_PICTURE_REFERENCES * sizeof(VAAPIEncodePicture *)) {
+        while (av_fifo_size(ctx->encode_fifo) <
+                MAX_ASYNC_DEPTH * sizeof(VAAPIEncodePicture *)) {
             pic = NULL;
             err = vaapi_encode_pick_next(avctx, &pic);
             if (err < 0)
@@ -1233,6 +1234,14 @@ int ff_vaapi_encode_receive_packet(AVCodecContext *avctx, AVPacket *pkt)
         }
         if (!av_fifo_size(ctx->encode_fifo))
             return err;
+        if (av_fifo_size(ctx->encode_fifo) <
+            ctx->async_depth * sizeof(VAAPIEncodePicture *) &&
+            !ctx->end_of_stream) {
+            av_fifo_generic_peek(ctx->encode_fifo, &pic, sizeof(pic), NULL);
+            err = vaapi_encode_wait(avctx, pic, 0);
+            if (err < 0)
+                return err;
+        }
         av_fifo_generic_read(ctx->encode_fifo, &pic, sizeof(pic), NULL);
         ctx->encode_order = pic->encode_order + 1;
     } else
@@ -1268,7 +1277,7 @@ int ff_vaapi_encode_receive_packet(AVCodecContext *avctx, AVPacket *pkt)
             pkt->dts = ctx->ts_ring[pic->encode_order] - ctx->dts_pts_diff;
     } else {
         pkt->dts = ctx->ts_ring[(pic->encode_order - ctx->decode_delay) %
-                                (3 * ctx->output_delay)];
+                                (3 * ctx->output_delay + ctx->async_depth)];
     }
     av_log(avctx, AV_LOG_DEBUG, "Output packet: pts %"PRId64" dts %"PRId64".\n",
            pkt->pts, pkt->dts);
@@ -2589,7 +2598,7 @@ av_cold int ff_vaapi_encode_init(AVCodecContext *avctx)
     vas = vaSyncBuffer(ctx->hwctx->display, 0, 0);
     if (vas != VA_STATUS_ERROR_UNIMPLEMENTED) {
         ctx->has_sync_buffer_func = 1;
-        ctx->encode_fifo = av_fifo_alloc((MAX_PICTURE_REFERENCES + 1) *
+        ctx->encode_fifo = av_fifo_alloc(MAX_ASYNC_DEPTH *
                                         sizeof(VAAPIEncodePicture *));
         if (!ctx->encode_fifo)
             return AVERROR(ENOMEM);
diff --git a/libavcodec/vaapi_encode.h b/libavcodec/vaapi_encode.h
index 560a1c42a9..1a5824e702 100644
--- a/libavcodec/vaapi_encode.h
+++ b/libavcodec/vaapi_encode.h
@@ -48,6 +48,7 @@ enum {
     MAX_TILE_ROWS          = 22,
     // A.4.1: table A.6 allows at most 20 tile columns for any level.
     MAX_TILE_COLS          = 20,
+    MAX_ASYNC_DEPTH        = 64,
 };
 
 extern const AVCodecHWConfigInternal *const ff_vaapi_encode_hw_configs[];
@@ -298,7 +299,8 @@ typedef struct VAAPIEncodeContext {
     // Timestamp handling.
     int64_t         first_pts;
     int64_t         dts_pts_diff;
-    int64_t         ts_ring[MAX_REORDER_DELAY * 3];
+    int64_t         ts_ring[MAX_REORDER_DELAY * 3 +
+                            MAX_ASYNC_DEPTH];
 
     // Slice structure.
     int slice_block_rows;
@@ -350,6 +352,8 @@ typedef struct VAAPIEncodeContext {
     AVFifoBuffer *encode_fifo;
     //Whether the driver support vaSyncBuffer
     int has_sync_buffer_func;
+    //Max number of frame buffered in encoder.
+    int async_depth;
 } VAAPIEncodeContext;
 
 enum {
@@ -460,7 +464,11 @@ int ff_vaapi_encode_close(AVCodecContext *avctx);
     { "b_depth", \
       "Maximum B-frame reference depth", \
       OFFSET(common.desired_b_depth), AV_OPT_TYPE_INT, \
-      { .i64 = 1 }, 1, INT_MAX, FLAGS }
+      { .i64 = 1 }, 1, INT_MAX, FLAGS }, \
+    { "async_depth", "Maximum processing parallelism. " \
+      "Increase this to improve single channel performance", \
+      OFFSET(common.async_depth), AV_OPT_TYPE_INT, \
+      { .i64 = 4 }, 0, MAX_ASYNC_DEPTH, FLAGS }
 
 #define VAAPI_ENCODE_RC_MODE(name, desc) \
     { #name, desc, 0, AV_OPT_TYPE_CONST, { .i64 = RC_MODE_ ## name }, \
-- 
2.25.1