2017-02-18 10:28 GMT+08:00 Pavel Koshevoy <[email protected]>: > On Fri, Feb 17, 2017 at 1:55 AM, Steven Liu <[email protected]> wrote: > > commandline: > > ./ffmpeg -i ~/Downloads/test.wav -af atempo=1.5 -acodec aac -y > > output.aac > > > > play the output.aac, the sound is very shake, terrible. > > after this patch， > > play the sound is smooth > > > > Signed-off-by: Steven Liu <[email protected]> > > --- > > libavfilter/af_atempo.c | 17 +++++++---------- > > 1 file changed, 7 insertions(+), 10 deletions(-) > > > > diff --git a/libavfilter/af_atempo.c b/libavfilter/af_atempo.c > > index a487882..db2f981 100644 > > --- a/libavfilter/af_atempo.c > > +++ b/libavfilter/af_atempo.c > > @@ -123,6 +123,8 @@ typedef struct { > > // tempo scaling factor: > > double tempo; > > > > + int drift; > > + > > // a snapshot of previous fragment input and output position values > > // captured when the tempo scale factor was set most recently: > > int64_t origin[2]; > > @@ -179,6 +181,7 @@ static void yae_clear(ATempoContext *atempo) > > atempo->head = 0; > > atempo->tail = 0; > > > > + atempo->drift = 0; > > atempo->nfrag = 0; > > atempo->state = YAE_LOAD_FRAGMENT; > > > > @@ -696,21 +699,12 @@ static int yae_adjust_position(ATempoContext > *atempo) > > const AudioFragment *prev = yae_prev_frag(atempo); > > AudioFragment *frag = yae_curr_frag(atempo); > > > > - const double prev_output_position = > > - (double)(prev->position[1] - atempo->origin[1] + atempo->window > / 2); > > - > > - const double ideal_output_position = > > - (double)(prev->position[0] - atempo->origin[0] + atempo->window > / 2) / > > - atempo->tempo; > > - > > - const int drift = (int)(prev_output_position - > ideal_output_position); > > - > > const int delta_max = atempo->window / 2; > > const int correction = yae_align(frag, > > prev, > > atempo->window, > > delta_max, > > - drift, > > + atempo->drift, > > atempo->correlation, > > atempo->complex_to_real); > > > > @@ -722,6 +716,9 @@ static int yae_adjust_position(ATempoContext > *atempo) > > frag->nsamples = 0; > > } > > > > + // update cumulative correction drift counter: > > + atempo->drift += correction; > > + > > return correction; > > } > > > > > Essentially, what you are doing here is reverting > 0c77cdb491de7a178e4142cb6a24538eec6b4f64 > > libavfilter/af_atempo: Avoid round-off error build-up, ticket #2484 > > Current method for constraining fragment position drift suffers from > round-off error build up. > > Instead of calculating cumulative drift as a sum of input fragment > position corrections, it is more accurate to calculate drift as the > difference between current fragment position and the ideal position > specified by the tempo scale factor. > > > Can you open another ticket and attach your sample file to it so I can > see how terrible it really sounds, and attempt a less destructive > solution perhaps? Please attach your output file as well. > > Thank you, > Pavel.
Ok, tickets has been create; https://trac.ffmpeg.org/ticket/6157 _______________________________________________ ffmpeg-devel mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
