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authorJustin Ruggles <justin.ruggles@gmail.com>2008-01-05 18:39:55 +0000
committerJustin Ruggles <justin.ruggles@gmail.com>2008-01-05 18:39:55 +0000
commit646800f79ca478309fcf741e840ba5b5e795e533 (patch)
treea4c6757a57caab5c58b40386848f9c0bc031813b /libavcodec/ac3_parser.c
parent86ad4c7e1b79c7721aa254933d69757adc185ee5 (diff)
move E-AC3 header parsing to ff_ac3_parse_header()
Originally committed as revision 11420 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/ac3_parser.c')
-rw-r--r--libavcodec/ac3_parser.c84
1 files changed, 37 insertions, 47 deletions
diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c
index 1b396bf6ac..604dac186a 100644
--- a/libavcodec/ac3_parser.c
+++ b/libavcodec/ac3_parser.c
@@ -38,6 +38,7 @@ int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
{
GetBitContext gbc;
int frame_size_code;
+ int num_blocks;
memset(hdr, 0, sizeof(*hdr));
@@ -47,11 +48,13 @@ int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
if(hdr->sync_word != 0x0B77)
return AC3_PARSE_ERROR_SYNC;
- /* read ahead to bsid to make sure this is AC-3, not E-AC-3 */
+ /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
hdr->bitstream_id = show_bits_long(&gbc, 29) & 0x1F;
- if(hdr->bitstream_id > 10)
+ if(hdr->bitstream_id > 16)
return AC3_PARSE_ERROR_BSID;
+ if(hdr->bitstream_id <= 10) {
+ /* Normal AC-3 */
hdr->crc1 = get_bits(&gbc, 16);
hdr->sr_code = get_bits(&gbc, 2);
if(hdr->sr_code == 3)
@@ -81,6 +84,37 @@ int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
+ } else {
+ /* Enhanced AC-3 */
+ hdr->crc1 = 0;
+ skip_bits(&gbc, 2); // skip stream type
+ skip_bits(&gbc, 3); // skip substream id
+
+ hdr->frame_size = (get_bits(&gbc, 11) + 1) << 1;
+ if(hdr->frame_size < AC3_HEADER_SIZE)
+ return AC3_PARSE_ERROR_FRAME_SIZE;
+
+ hdr->sr_code = get_bits(&gbc, 2);
+ if (hdr->sr_code == 3) {
+ int sr_code2 = get_bits(&gbc, 2);
+ if(sr_code2 == 3)
+ return AC3_PARSE_ERROR_SAMPLE_RATE;
+ hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
+ hdr->sr_shift = 1;
+ num_blocks = 6;
+ } else {
+ num_blocks = eac3_blocks[get_bits(&gbc, 2)];
+ hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
+ hdr->sr_shift = 0;
+ }
+
+ hdr->channel_mode = get_bits(&gbc, 3);
+ hdr->lfe_on = get_bits1(&gbc);
+
+ hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
+ (num_blocks * 256.0));
+ hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
+ }
return 0;
}
@@ -89,62 +123,18 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
int *bit_rate, int *samples)
{
int err;
- unsigned int sr_code, channel_mode, bitstream_id, lfe_on;
- unsigned int stream_type, substream_id, frame_size, sr_code2, num_blocks_code;
- GetBitContext bits;
AC3HeaderInfo hdr;
err = ff_ac3_parse_header(buf, &hdr);
- if(err < 0 && err != -2)
+ if(err < 0)
return 0;
- bitstream_id = hdr.bitstream_id;
- if(bitstream_id <= 10) { /* Normal AC-3 */
*sample_rate = hdr.sample_rate;
*bit_rate = hdr.bit_rate;
*channels = hdr.channels;
*samples = AC3_FRAME_SIZE;
return hdr.frame_size;
- } else if (bitstream_id > 10 && bitstream_id <= 16) { /* Enhanced AC-3 */
- init_get_bits(&bits, &buf[2], (AC3_HEADER_SIZE-2) * 8);
- stream_type = get_bits(&bits, 2);
- substream_id = get_bits(&bits, 3);
-
- if (stream_type != 0 || substream_id != 0)
- return 0; /* Currently don't support additional streams */
-
- frame_size = get_bits(&bits, 11) + 1;
- if(frame_size*2 < AC3_HEADER_SIZE)
- return 0;
-
- sr_code = get_bits(&bits, 2);
- if (sr_code == 3) {
- sr_code2 = get_bits(&bits, 2);
- num_blocks_code = 3;
-
- if(sr_code2 == 3)
- return 0;
-
- *sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
- } else {
- num_blocks_code = get_bits(&bits, 2);
-
- *sample_rate = ff_ac3_sample_rate_tab[sr_code];
- }
-
- channel_mode = get_bits(&bits, 3);
- lfe_on = get_bits1(&bits);
-
- *samples = eac3_blocks[num_blocks_code] * 256;
- *bit_rate = frame_size * (*sample_rate) * 16 / (*samples);
- *channels = ff_ac3_channels_tab[channel_mode] + lfe_on;
-
- return frame_size * 2;
- }
-
- /* Unsupported bitstream version */
- return 0;
}
static int ac3_parse_init(AVCodecParserContext *s1)