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Code Issues Releases Activity

Use bytes instead of 16-bit words for frame size.

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Originally committed as revision 25977 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2010-12-14 14:52:14 +00:00
parent eed00252c9
commit 427e2293d3
1 changed files with 14 additions and 14 deletions
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28
libavcodec/ac3enc.c
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@ -65,7 +65,7 @@ typedef struct AC3EncodeContext {
int sample_rate; ///< sampling frequency, in Hz
int frame_size_min; ///< minimum frame size in case rounding is necessary
int frame_size; ///< current frame size in words
int frame_size; ///< current frame size in bytes
int frame_size_code; ///< frame size code (frmsizecod)
int bits_written; ///< bit count (used to avg. bitrate)
int samples_written; ///< sample count (used to avg. bitrate)
@ -562,7 +562,7 @@ static int bit_alloc(AC3EncodeContext *s,
frame_bits += compute_mantissa_size(s, bap[blk][ch], s->nb_coefs[ch]);
}
}
return 16 * s->frame_size - frame_bits;
return 8 * s->frame_size - frame_bits;
}
@ -699,7 +699,7 @@ static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
put_bits(&s->pb, 16, 0x0b77); /* frame header */
put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
put_bits(&s->pb, 2, s->bit_alloc.sr_code);
put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min));
put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
put_bits(&s->pb, 5, s->bitstream_id);
put_bits(&s->pb, 3, s->bitstream_mode);
put_bits(&s->pb, 3, s->channel_mode);
@ -1048,27 +1048,27 @@ static void output_frame_end(AC3EncodeContext *s)
flush_put_bits(&s->pb);
/* add zero bytes to reach the frame size */
frame = s->pb.buf;
pad_bytes = 2 * s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
assert(pad_bytes >= 0);
if (pad_bytes > 0)
memset(put_bits_ptr(&s->pb), 0, pad_bytes);
/* Now we must compute both crcs : this is not so easy for crc1
because it is at the beginning of the data... */
frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
frame_size_58 = ((frame_size >> 2) + (frame_size >> 4)) << 1;
crc1 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
frame + 4, 2 * frame_size_58 - 4));
frame + 4, frame_size_58 - 4));
/* XXX: could precompute crc_inv */
crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
crc_inv = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
AV_WB16(frame + 2, crc1);
crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
frame + 2 * frame_size_58,
(frame_size - frame_size_58) * 2 - 2));
AV_WB16(frame + 2*frame_size - 2, crc2);
frame + frame_size_58,
frame_size - frame_size_58 - 2));
AV_WB16(frame + frame_size - 2, crc2);
}
@ -1174,8 +1174,8 @@ static int ac3_encode_frame(AVCodecContext *avctx,
s->bits_written -= s->bit_rate;
s->samples_written -= s->sample_rate;
}
s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
s->bits_written += s->frame_size * 16;
s->frame_size = s->frame_size_min + 2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
s->bits_written += s->frame_size * 8;
s->samples_written += AC3_FRAME_SIZE;
compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
@ -1188,7 +1188,7 @@ static int ac3_encode_frame(AVCodecContext *avctx,
}
output_frame_end(s);
return s->frame_size * 2;
return s->frame_size;
}
@ -1298,7 +1298,7 @@ static av_cold int ac3_encode_init(AVCodecContext *avctx)
return -1;
s->bit_rate = bitrate;
s->frame_size_code = i << 1;
s->frame_size_min = ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
s->frame_size_min = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
s->bits_written = 0;
s->samples_written = 0;
s->frame_size = s->frame_size_min;