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Code Issues Releases Activity

Store CRC context locally to reduce number of calls to av_crc_get_table().

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Originally committed as revision 26082 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2010-12-23 18:01:23 +00:00
parent 0e9b064305
commit a897423baa
1 changed files with 3 additions and 2 deletions
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5
libavcodec/ac3enc.c
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@ -1571,6 +1571,7 @@ static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
*/
static void output_frame_end(AC3EncodeContext *s)
{
const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
int frame_size_58, pad_bytes, crc1, crc2, crc_inv;
uint8_t *frame;
@ -1586,14 +1587,14 @@ static void output_frame_end(AC3EncodeContext *s)
/* compute crc1 */
/* this is not so easy because it is at the beginning of the data... */
crc1 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
crc1 = av_bswap16(av_crc(crc_ctx, 0,
frame + 4, frame_size_58 - 4));
crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
AV_WB16(frame + 2, crc1);
/* compute crc2 */
crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
crc2 = av_bswap16(av_crc(crc_ctx, 0,
frame + frame_size_58,
s->frame_size - frame_size_58 - 2));
AV_WB16(frame + s->frame_size - 2, crc2);