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gst/mpegaudioparse/gstmpegaudioparse.c: Fix header parsing - stolen from ffmpeg (thank you! :) ).

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Original commit message from CVS:
2004-01-30  Ronald Bultje  <rbultje@ronald.bitfreak.net>

* gst/mpegaudioparse/gstmpegaudioparse.c:
(mp3_type_frame_length_from_header):
Fix header parsing - stolen from ffmpeg (thank you! :) ).
This commit is contained in:
Ronald S. Bultje 2004-01-30 14:23:18 +00:00
parent d6b53a5d14
commit c51720c929
2 changed files with 38 additions and 50 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2004-01-30 Ronald Bultje <rbultje@ronald.bitfreak.net>
* gst/mpegaudioparse/gstmpegaudioparse.c:
(mp3_type_frame_length_from_header):
Fix header parsing - stolen from ffmpeg (thank you! :) ).
2004-01-30 Ronald Bultje <rbultje@ronald.bitfreak.net>
* ext/esd/esdsink.c: (gst_esdsink_init):

82
gst/mpegaudioparse/gstmpegaudioparse.c
View file

@ -127,61 +127,43 @@ mp3_type_frame_length_from_header (guint32 header, guint *put_layer,
guint *put_samplerate)
{
guint length;
gulong mode, samplerate, bitrate, layer, version, channels;
gulong mode, samplerate, bitrate, layer, channels, padding;
gint lsf, mpg25;
/* we don't need extension, copyright, original or
* emphasis for the frame length */
header >>= 6;
/* mode */
mode = header & 0x3;
header >>= 3;
/* padding */
length = header & 0x1;
header >>= 1;
/* sampling frequency */
samplerate = header & 0x3;
if (samplerate == 3)
return 0;
header >>= 2;
/* bitrate index */
bitrate = header & 0xF;
if (bitrate == 15 || bitrate == 0)
return 0;
/* ignore error correction, too */
header >>= 5;
/* layer */
layer = 4 - (header & 0x3);
if (layer == 4)
return 0;
header >>= 2;
/* version */
version = header & 0x3;
if (version == 1)
return 0;
/* lookup */
channels = (mode == 3) ? 1 : 2;
bitrate = mp3types_bitrates[version == 3 ? 0 : 1][layer - 1][bitrate];
samplerate = mp3types_freqs[version > 0 ? version - 1 : 0][samplerate];
/* calculating */
if (layer == 1) {
length = ((12000 * bitrate / samplerate) + length) * 4;
if (header & (1 << 20)) {
lsf = (header & (1 << 19)) ? 0 : 1;
mpg25 = 0;
} else {
length += ((layer == 3 && version == 0) ? 144000 : 72000) * bitrate / samplerate;
lsf = 1;
mpg25 = 1;
}
mode = (header >> 6) & 0x3;
channels = (mode == 3) ? 1 : 2;
samplerate = (header >> 10) & 0x3;
samplerate = mp3types_freqs[lsf + mpg25][samplerate];
layer = 4 - ((header >> 17) & 0x3);
bitrate = (header >> 12) & 0xF;
bitrate = mp3types_bitrates[lsf][layer - 1][bitrate] * 1000;
if (bitrate == 0)
return 0;
padding = (header >> 9) & 0x1;
switch (layer) {
case 1:
length = (bitrate * 12) / samplerate + 4 * padding;
break;
case 2:
length = (bitrate * 144) / samplerate + padding;
break;
default:
case 3:
length = (bitrate * 144) / (samplerate << lsf) + padding;
break;
}
GST_DEBUG ("Calculated mp3 frame length of %u bytes", length);
GST_DEBUG ("samplerate = %lu - bitrate = %lu - layer = %lu - version = %lu"
" - channels = %lu",
samplerate, bitrate, layer, version, channels);
GST_DEBUG ("samplerate = %lu, bitrate = %lu, layer = %lu, channels = %lu",
samplerate, bitrate, layer, channels);
if (put_layer)
*put_layer = layer;