Attached patch solves the overshoots the encoder has.
From 5e4e428fdf3fcc58431b80947dc399dfacb82724 Mon Sep 17 00:00:00 2001
From: Rostislav Pehlivanov <rpehliva...@obe.tv>
Date: Wed, 6 Apr 2016 11:51:24 +0100
Subject: [PATCH] vc2enc: prevent bitrate overshoots
The rounding caused by the size scaler wasn't compensated for and the
slice sizes grew beyond what is allowed per frame.
Signed-off-by: Rostislav Pehlivanov <rpehliva...@obe.tv>
---
libavcodec/vc2enc.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/libavcodec/vc2enc.c b/libavcodec/vc2enc.c
index 577d49d..fdbd0d4 100644
--- a/libavcodec/vc2enc.c
+++ b/libavcodec/vc2enc.c
@@ -167,6 +167,7 @@ typedef struct VC2EncContext {
int chroma_y_shift;
/* Rate control stuff */
+ int frame_max_bytes;
int slice_max_bytes;
int slice_min_bytes;
int q_ceil;
@@ -718,7 +719,7 @@ static int calc_slice_sizes(VC2EncContext *s)
for (i = 0; i < s->num_x*s->num_y; i++) {
SliceArgs *args = &enc_args[i];
- bytes_left += s->slice_max_bytes - args->bytes;
+ bytes_left += args->bytes;
for (j = 0; j < slice_redist_range; j++) {
if (args->bytes > bytes_top[j]) {
bytes_top[j] = args->bytes;
@@ -728,8 +729,10 @@ static int calc_slice_sizes(VC2EncContext *s)
}
}
+ bytes_left = s->frame_max_bytes - bytes_left;
+
/* Second pass - distribute leftover bytes */
- while (1) {
+ while (bytes_left > 0) {
int distributed = 0;
for (i = 0; i < slice_redist_range; i++) {
SliceArgs *args;
@@ -992,12 +995,12 @@ static av_cold int vc2_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
const AVFrame *frame, int *got_packet)
{
int ret = 0;
- int sig_size = 256;
+ int slice_ceil, sig_size = 256;
VC2EncContext *s = avctx->priv_data;
const char aux_data[] = LIBAVCODEC_IDENT;
const int aux_data_size = sizeof(aux_data);
const int header_size = 100 + aux_data_size;
- int64_t max_frame_bytes, r_bitrate = avctx->bit_rate >> (s->interlaced);
+ int64_t r_bitrate = avctx->bit_rate >> (s->interlaced);
s->avctx = avctx;
s->size_scaler = 2;
@@ -1006,18 +1009,21 @@ static av_cold int vc2_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
s->next_parse_offset = 0;
/* Rate control */
- max_frame_bytes = (av_rescale(r_bitrate, s->avctx->time_base.num,
- s->avctx->time_base.den) >> 3) - header_size;
- s->slice_max_bytes = av_rescale(max_frame_bytes, 1, s->num_x*s->num_y);
+ s->frame_max_bytes = (av_rescale(r_bitrate, s->avctx->time_base.num,
+ s->avctx->time_base.den) >> 3) - header_size;
+ s->slice_max_bytes = slice_ceil = av_rescale(s->frame_max_bytes, 1, s->num_x*s->num_y);
/* Find an appropriate size scaler */
while (sig_size > 255) {
int r_size = SSIZE_ROUND(s->slice_max_bytes);
+ if (r_size > slice_ceil) {
+ s->slice_max_bytes -= r_size - slice_ceil;
+ r_size = SSIZE_ROUND(s->slice_max_bytes);
+ }
sig_size = r_size/s->size_scaler; /* Signalled slize size */
s->size_scaler <<= 1;
}
- s->slice_max_bytes = SSIZE_ROUND(s->slice_max_bytes);
s->slice_min_bytes = s->slice_max_bytes - s->slice_max_bytes*(s->tolerance/100.0f);
ret = encode_frame(s, avpkt, frame, aux_data, header_size, s->interlaced);
--
2.8.0.rc3
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