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swr: add swr_get_delay() to find the exact delay the swresampler introduces. 

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-05-18 23:02:10 +02:00
parent 6ba692f8a7
commit 4def5d2b64
2 changed files with 34 additions and 1 deletions
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15
libswresample/resample.c
View File

@ -367,3 +367,18 @@ int swri_multiple_resample(ResampleContext *c, AudioData *dst, int dst_size, Aud
return ret;
}
int64_t swr_get_delay(struct SwrContext *s, int64_t base){
ResampleContext *c = s->resample;
if(c){
int64_t num = s->in_buffer_count - (c->filter_length-1)/2;
num <<= c->phase_shift;
num -= c->index;
num *= c->src_incr;
num -= c->frac;
return av_rescale(num, base, s->in_sample_rate*(int64_t)c->src_incr << c->phase_shift);
}else{
return (s->in_buffer_count*base + (s->in_sample_rate>>1))/ s->in_sample_rate;
}
}

20
libswresample/swresample.h
View File

@ -30,7 +30,7 @@
#include "libavutil/samplefmt.h"
#define LIBSWRESAMPLE_VERSION_MAJOR 0
#define LIBSWRESAMPLE_VERSION_MINOR 11
#define LIBSWRESAMPLE_VERSION_MINOR 12
#define LIBSWRESAMPLE_VERSION_MICRO 100
#define LIBSWRESAMPLE_VERSION_INT AV_VERSION_INT(LIBSWRESAMPLE_VERSION_MAJOR, \
@ -158,6 +158,24 @@ int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map);
*/
int swr_set_matrix(struct SwrContext *s, const double *matrix, int stride);
/**
* Gets the delay the next input sample will experience relative to the next output sample.
*
* Swresample can buffer data if more input has been provided than available
* output space, also converting between sample rates needs a delay.
* This function returns the sum of all such delays.
*
* @param s swr context
* @param base timebase in which the returned delay will be
* if its set to 1 the returned delay is in seconds
* if its set to 1000 the returned delay is in milli seconds
* if its set to the input sample rate then the returned delay is in input samples
* if its set to the output sample rate then the returned delay is in output samples
* an exact rounding free delay can be found by using LCM(in_sample_rate, out_sample_rate)
* @returns the delay in 1/base units.
*/
int64_t swr_get_delay(struct SwrContext *s, int64_t base);
/**
* Return the LIBSWRESAMPLE_VERSION_INT constant.
*/