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alacenc: calculate a new max frame size for the final small frame 

Gives a better estimate of buffer requirements and a better decision of
whether or not to use verbatim mode.
This commit is contained in:
Justin Ruggles 2012-02-02 16:03:41 -05:00
parent fc9cf0b2a6
commit 302daf5800
1 changed files with 17 additions and 4 deletions
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21
libavcodec/alacenc.c
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@ -377,6 +377,11 @@ static void write_compressed_frame(AlacEncodeContext *s)
}
}
static av_always_inline int get_max_frame_size(int frame_size, int ch, int bps)
{
return FFALIGN(55 + bps * ch * frame_size + 3, 8) / 8;
}
static av_cold int alac_encode_close(AVCodecContext *avctx)
{
AlacEncodeContext *s = avctx->priv_data;
@ -420,8 +425,9 @@ static av_cold int alac_encode_init(AVCodecContext *avctx)
s->rc.k_modifier = 14;
s->rc.rice_modifier = 4;
s->max_coded_frame_size = 8 + (avctx->frame_size * avctx->channels *
DEFAULT_SAMPLE_SIZE >> 3);
s->max_coded_frame_size = get_max_frame_size(avctx->frame_size,
avctx->channels,
DEFAULT_SAMPLE_SIZE);
// FIXME: consider wasted_bytes
s->write_sample_size = DEFAULT_SAMPLE_SIZE + avctx->channels - 1;
@ -511,8 +517,15 @@ static int alac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
AlacEncodeContext *s = avctx->priv_data;
PutBitContext *pb = &s->pbctx;
int i, out_bytes, verbatim_flag = 0;
int max_frame_size;
if (buf_size < 2 * s->max_coded_frame_size) {
if (avctx->frame_size < DEFAULT_FRAME_SIZE)
max_frame_size = get_max_frame_size(avctx->frame_size, avctx->channels,
DEFAULT_SAMPLE_SIZE);
else
max_frame_size = s->max_coded_frame_size;
if (buf_size < 2 * max_frame_size) {
av_log(avctx, AV_LOG_ERROR, "buffer size is too small\n");
return -1;
}
@ -537,7 +550,7 @@ verbatim:
flush_put_bits(pb);
out_bytes = put_bits_count(pb) >> 3;
if (out_bytes > s->max_coded_frame_size) {
if (out_bytes > max_frame_size) {
/* frame too large. use verbatim mode */
if (verbatim_flag || s->compression_level == 0) {
/* still too large. must be an error. */