[FFmpeg-devel] [PATCH 2/2] lavc/vaapi_encode: fix the mismatched vbvBuf size unit for mpeg2

Linjie Fu linjie.fu at intel.com
Wed Jan 16 16:34:45 EET 2019


hrd_buffer_size and hrd_initial_buffer_fullness are set in bits, while
driver takes the vbvBuf size in 16 kbits. The mismatch will cause
quality issue.

One way to solve this issue in FFmpeg level is set the bufsize
specially for mpeg2 as the unit of 16 kbits, and discard the default
CBR mode in driver.

Fix the quality issue in #7650.

Signed-off-by: Linjie Fu <linjie.fu at intel.com>
---
 libavcodec/vaapi_encode.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/libavcodec/vaapi_encode.c b/libavcodec/vaapi_encode.c
index eda8a36299..c932d9d7fb 100644
--- a/libavcodec/vaapi_encode.c
+++ b/libavcodec/vaapi_encode.c
@@ -1305,9 +1305,11 @@ static av_cold int vaapi_encode_init_rate_control(AVCodecContext *avctx)
     if (avctx->rc_buffer_size)
         hrd_buffer_size = avctx->rc_buffer_size;
     else if (avctx->rc_max_rate > 0)
-        hrd_buffer_size = avctx->rc_max_rate;
+        hrd_buffer_size = ctx->codec->profiles->va_profile > 1 ?
+                        avctx->rc_max_rate : avctx->rc_max_rate >> 14;
     else
-        hrd_buffer_size = avctx->bit_rate;
+        hrd_buffer_size = ctx->codec->profiles->va_profile > 1 ?
+                        avctx->bit_rate : avctx->bit_rate >> 14;
     if (avctx->rc_initial_buffer_occupancy) {
         if (avctx->rc_initial_buffer_occupancy > hrd_buffer_size) {
             av_log(avctx, AV_LOG_ERROR, "Invalid RC buffer settings: "
@@ -1318,7 +1320,7 @@ static av_cold int vaapi_encode_init_rate_control(AVCodecContext *avctx)
         }
         hrd_initial_buffer_fullness = avctx->rc_initial_buffer_occupancy;
     } else {
-        hrd_initial_buffer_fullness = hrd_buffer_size * 3 / 4;
+        hrd_initial_buffer_fullness = FFMAX(avctx->bit_rate, avctx->rc_max_rate) * 3 / 4;
     }
 
     if (avctx->rc_max_rate && avctx->rc_max_rate < avctx->bit_rate) {
-- 
2.17.1



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