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flacparse: Simplify frame header parsing by using lookup tables

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Based on a patch by Felipe Contreras.

See bug #631200.
This commit is contained in:
Sebastian Dröge 2010-10-07 23:37:36 +02:00
parent 64407ca94b
commit 812075dc5d
1 changed files with 23 additions and 39 deletions
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62
gst/audioparsers/gstflacparse.c
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@ -351,6 +351,21 @@ gst_flac_parse_stop (GstBaseParse * parse)
return TRUE;
}
static const guint8 sample_size_table[] = { 0, 8, 12, 0, 16, 20, 24, 0 };
static const guint16 blocksize_table[16] = {
0, 192, 576 << 0, 576 << 1, 576 << 2, 576 << 3, 0, 0,
256 << 0, 256 << 1, 256 << 2, 256 << 3, 256 << 4, 256 << 5, 256 << 6,
256 << 7,
};
static const guint32 sample_rate_table[16] = {
0,
88200, 176400, 192000,
8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
0, 0, 0, 0,
};
typedef enum
{
FRAME_HEADER_VALID,
@ -409,17 +424,8 @@ gst_flac_parse_frame_header_is_valid (GstFlacParse * flacparse,
goto error;
} else if (bps == 0 && flacparse->bps == 0) {
goto need_streaminfo;
} else if (tmp == 0x01) {
bps = 8;
} else if (bps == 0x02) {
bps = 12;
} else if (bps == 0x04) {
bps = 16;
} else if (bps == 0x05) {
bps = 20;
} else if (bps == 0x06) {
bps = 24;
}
bps = sample_size_table[bps];
if (flacparse->bps && bps != flacparse->bps)
goto error;
@ -477,13 +483,9 @@ gst_flac_parse_frame_header_is_valid (GstFlacParse * flacparse,
}
/* calculate real blocksize from the blocksize index */
if (block_size == 1)
block_size = 192;
else if (block_size <= 5)
block_size = 576 * (1 << (block_size - 2));
else if (block_size <= 15)
block_size = 256 * (1 << (block_size - 8));
else if (block_size == 6) {
if (block_size == 0) {
goto error;
} else if (block_size == 6) {
if (!gst_bit_reader_get_bits_uint16 (&reader, &block_size, 8))
goto need_more_data;
block_size++;
@ -491,33 +493,15 @@ gst_flac_parse_frame_header_is_valid (GstFlacParse * flacparse,
if (!gst_bit_reader_get_bits_uint16 (&reader, &block_size, 16))
goto need_more_data;
block_size++;
} else {
block_size = blocksize_table[block_size];
}
/* calculate the real samplerate from the samplerate index */
if (samplerate == 0 && flacparse->samplerate == 0) {
goto need_streaminfo;
} else if (samplerate == 1) {
samplerate = 88200;
} else if (samplerate == 2) {
samplerate = 176400;
} else if (samplerate == 3) {
samplerate = 192000;
} else if (samplerate == 4) {
samplerate = 8000;
} else if (samplerate == 5) {
samplerate = 16000;
} else if (samplerate == 6) {
samplerate = 22050;
} else if (samplerate == 7) {
samplerate = 24000;
} else if (samplerate == 8) {
samplerate = 32000;
} else if (samplerate == 9) {
samplerate = 44100;
} else if (samplerate == 10) {
samplerate = 48000;
} else if (samplerate == 11) {
samplerate = 96000;
} else if (samplerate < 12) {
samplerate = sample_rate_table[samplerate];
} else if (samplerate == 12) {
if (!gst_bit_reader_get_bits_uint32 (&reader, &samplerate, 8))
goto need_more_data;