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avcodec/vc2enc: prevent bitrate overshoots

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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 <rpehlivanov@obe.tv>
This commit is contained in:
Rostislav Pehlivanov 2016-04-06 11:51:24 +01:00 committed by James Darnley
parent fe1e6c06d0
commit 61a4ee8ab4
1 changed files with 14 additions and 8 deletions
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22
libavcodec/vc2enc.c
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@ -164,6 +164,7 @@ 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;
@ -715,7 +716,7 @@ 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;
@ -725,8 +726,10 @@ 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;
@ -994,13 +997,13 @@ 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 int bitexact = avctx->flags & AV_CODEC_FLAG_BITEXACT;
const char *aux_data = bitexact ? "Lavc" : LIBAVCODEC_IDENT;
const int aux_data_size = bitexact ? sizeof("Lavc") : sizeof(LIBAVCODEC_IDENT);
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;
@ -1009,18 +1012,21 @@ 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);