On 06/13/2018 07:39 AM, Pavel Koshevoy wrote:
On Thu, Jun 7, 2018 at 8:16 PM Pavel Koshevoy <pkoshe...@gmail.com> wrote:
---
doc/filters.texi | 17 ++++++++++++++---
libavfilter/af_atempo.c | 6 +++---
2 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 256ab42b00..6b98b04774 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1986,7 +1986,12 @@ Adjust audio tempo.
The filter accepts exactly one parameter, the audio tempo. If not
specified then the filter will assume nominal 1.0 tempo. Tempo must
-be in the [0.5, 2.0] range.
+be in the [0.5, 100.0] range.
+
+Note that tempo greater than 2 will skip some samples rather than
+blend them in. If for any reason this is a concern it is always
+possible to daisy-chain several instances of atempo to achieve the
+desired product tempo.
@subsection Examples
@@ -1998,9 +2003,15 @@ atempo=0.8
@end example
@item
-To speed up audio to 125% tempo:
+To speed up audio to 300% tempo:
+@example
+atempo=3
+@end example
+
+@item
+To speed up audio to 300% tempo by daisy-chaining two atempo instances:
@example
-atempo=1.25
+atempo=sqrt(3),atempo=sqrt(3)
@end example
@end itemize
diff --git a/libavfilter/af_atempo.c b/libavfilter/af_atempo.c
index 8b214bccd7..52f15f2769 100644
--- a/libavfilter/af_atempo.c
+++ b/libavfilter/af_atempo.c
@@ -153,7 +153,7 @@ typedef struct ATempoContext {
static const AVOption atempo_options[] = {
{ "tempo", "set tempo scale factor",
- OFFSET(tempo), AV_OPT_TYPE_DOUBLE, { .dbl = 1.0 }, 0.5, 2.0,
+ OFFSET(tempo), AV_OPT_TYPE_DOUBLE, { .dbl = 1.0 }, 0.5, 100.0,
AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM },
{ NULL }
};
@@ -439,8 +439,8 @@ static int yae_load_data(ATempoContext *atempo,
return 0;
}
- // samples are not expected to be skipped:
- av_assert0(read_size <= atempo->ring);
+ // samples are not expected to be skipped, unless tempo is greater than 2:
+ av_assert0(read_size <= atempo->ring || atempo->tempo > 2.0);
while (atempo->position[0] < stop_here && src < src_end) {
int src_samples = (src_end - src) / atempo->stride;
--
2.16.4
Any objections if I apply this?
Pavel.
Applied, pushed
Pavel.
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