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aac: moved code to adts_check_frame()

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adts_check_frame() checks whether the buffer head is an AAC frame, and
returns the frame length.
This commit is contained in:
Max Kellermann 2008-08-26 08:27:11 +02:00
parent b7ad3e4121
commit f43e39047d
1 changed files with 20 additions and 11 deletions
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31
src/inputPlugins/aac_plugin.c
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@ -93,6 +93,24 @@ static int adtsSampleRates[] =
16000, 12000, 11025, 8000, 7350, 0, 0, 0 16000, 12000, 11025, 8000, 7350, 0, 0, 0
}; };
/**
* Check whether the buffer head is an AAC frame, and return the frame
* length. Returns 0 if it is not a frame.
*/
static size_t adts_check_frame(AacBuffer * b)
{
if (b->bytesIntoBuffer <= 7)
return 0;
/* check syncword */
if (!((b->buffer[0] == 0xFF) && ((b->buffer[1] & 0xF6) == 0xF0)))
return 0;
return (((unsigned int)b->buffer[3] & 0x3) << 11) |
(((unsigned int)b->buffer[4]) << 3) |
(b->buffer[5] >> 5);
}
static void adtsParse(AacBuffer * b, float *length) static void adtsParse(AacBuffer * b, float *length)
{ {
unsigned int frames, frameLength; unsigned int frames, frameLength;
@ -103,23 +121,14 @@ static void adtsParse(AacBuffer * b, float *length)
for (frames = 0;; frames++) { for (frames = 0;; frames++) {
fillAacBuffer(b); fillAacBuffer(b);
if (b->bytesIntoBuffer > 7) { frameLength = adts_check_frame(b);
/* check syncword */ if (frameLength > 0) {
if (!((b->buffer[0] == 0xFF) &&
((b->buffer[1] & 0xF6) == 0xF0))) {
break;
}
if (frames == 0) { if (frames == 0) {
sampleRate = adtsSampleRates[(b-> sampleRate = adtsSampleRates[(b->
buffer[2] & 0x3c) buffer[2] & 0x3c)
>> 2]; >> 2];
} }
frameLength = ((((unsigned int)b->buffer[3] & 0x3))
<< 11) | (((unsigned int)b->buffer[4])
<< 3) | (b->buffer[5] >> 5);
if (frameLength > b->bytesIntoBuffer) if (frameLength > b->bytesIntoBuffer)
break; break;