avfilter: add loop filters

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -4,6 +4,7 @@ releases are sorted from youngest to oldest.
 version <next>:
 - DXVA2-accelerated HEVC Main10 decoding
 - fieldhint filter
+- loop video filter and aloop audio filter
 
 
 version 3.0:

doc/APIchanges

@@ -15,6 +15,9 @@ libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2016-xx-xx - lavu 55.18.100
+  xxxxxxx audio_fifo.h - Add av_audio_fifo_peek_at().
+
 2016-xx-xx - lavu 55.18.0
   xxxxxxx buffer.h - Add av_buffer_pool_init2().
   xxxxxxx hwcontext.h - Add a new installed header hwcontext.h with a new API

doc/filters.texi

@@ -8185,6 +8185,25 @@ The formula that generates the correction is:
 where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
 distances from the focal point in the source and target images, respectively.
 
+@section loop, aloop
+
+Loop video frames or audio samples.
+
+Those filters accepts the following options:
+
+@table @option
+@item loop
+Set the number of loops.
+
+@item size
+Set maximal size in number of frames for @code{loop} filter or maximal number
+of samples in case of @code{aloop} filter.
+
+@item start
+Set first frame of loop for @code{loop} filter or first sample of loop in case
+of @code{aloop} filter.
+@end table
+
 @anchor{lut3d}
 @section lut3d
 

libavfilter/Makefile

@@ -38,6 +38,7 @@ OBJS-$(CONFIG_AGATE_FILTER)                  += af_agate.o
 OBJS-$(CONFIG_AINTERLEAVE_FILTER)            += f_interleave.o
 OBJS-$(CONFIG_ALIMITER_FILTER)               += af_alimiter.o
 OBJS-$(CONFIG_ALLPASS_FILTER)                += af_biquads.o
+OBJS-$(CONFIG_ALOOP_FILTER)                  += f_loop.o
 OBJS-$(CONFIG_AMERGE_FILTER)                 += af_amerge.o
 OBJS-$(CONFIG_AMETADATA_FILTER)              += f_metadata.o
 OBJS-$(CONFIG_AMIX_FILTER)                   += af_amix.o
@@ -181,6 +182,7 @@ OBJS-$(CONFIG_INTERLACE_FILTER)              += vf_interlace.o
 OBJS-$(CONFIG_INTERLEAVE_FILTER)             += f_interleave.o
 OBJS-$(CONFIG_KERNDEINT_FILTER)              += vf_kerndeint.o
 OBJS-$(CONFIG_LENSCORRECTION_FILTER)         += vf_lenscorrection.o
+OBJS-$(CONFIG_LOOP_FILTER)                   += f_loop.o
 OBJS-$(CONFIG_LUT3D_FILTER)                  += vf_lut3d.o
 OBJS-$(CONFIG_LUT_FILTER)                    += vf_lut.o
 OBJS-$(CONFIG_LUTRGB_FILTER)                 += vf_lut.o

libavfilter/allfilters.c

@@ -58,6 +58,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(AINTERLEAVE,    ainterleave,    af);
     REGISTER_FILTER(ALIMITER,       alimiter,       af);
     REGISTER_FILTER(ALLPASS,        allpass,        af);
+    REGISTER_FILTER(ALOOP,          aloop,          af);
     REGISTER_FILTER(AMERGE,         amerge,         af);
     REGISTER_FILTER(AMETADATA,      ametadata,      af);
     REGISTER_FILTER(AMIX,           amix,           af);
@@ -202,6 +203,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(INTERLEAVE,     interleave,     vf);
     REGISTER_FILTER(KERNDEINT,      kerndeint,      vf);
     REGISTER_FILTER(LENSCORRECTION, lenscorrection, vf);
+    REGISTER_FILTER(LOOP,           loop,           vf);
     REGISTER_FILTER(LUT3D,          lut3d,          vf);
     REGISTER_FILTER(LUT,            lut,            vf);
     REGISTER_FILTER(LUTRGB,         lutrgb,         vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  32
+#define LIBAVFILTER_VERSION_MINOR  33
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavutil/audio_fifo.c

@@ -155,6 +155,30 @@ int av_audio_fifo_peek(AVAudioFifo *af, void **data, int nb_samples)
     return nb_samples;
 }
 
+int av_audio_fifo_peek_at(AVAudioFifo *af, void **data, int nb_samples, int offset)
+{
+    int i, ret, size;
+
+    if (offset < 0 || offset >= af->nb_samples)
+        return AVERROR(EINVAL);
+    if (nb_samples < 0)
+        return AVERROR(EINVAL);
+    nb_samples = FFMIN(nb_samples, af->nb_samples);
+    if (!nb_samples)
+        return 0;
+    if (offset > af->nb_samples - nb_samples)
+        return AVERROR(EINVAL);
+
+    offset *= af->sample_size;
+    size = nb_samples * af->sample_size;
+    for (i = 0; i < af->nb_buffers; i++) {
+        if ((ret = av_fifo_generic_peek_at(af->buf[i], data[i], offset, size, NULL)) < 0)
+            return AVERROR_BUG;
+    }
+
+    return nb_samples;
+}
+
 int av_audio_fifo_read(AVAudioFifo *af, void **data, int nb_samples)
 {
     int i, ret, size;

libavutil/audio_fifo.h

@@ -110,6 +110,23 @@ int av_audio_fifo_write(AVAudioFifo *af, void **data, int nb_samples);
  */
 int av_audio_fifo_peek(AVAudioFifo *af, void **data, int nb_samples);
 
+/**
+ * Peek data from an AVAudioFifo.
+ *
+ * @see enum AVSampleFormat
+ * The documentation for AVSampleFormat describes the data layout.
+ *
+ * @param af          AVAudioFifo to read from
+ * @param data        audio data plane pointers
+ * @param nb_samples  number of samples to peek
+ * @param offset      offset from current read position
+ * @return            number of samples actually peek, or negative AVERROR code
+ *                    on failure. The number of samples actually peek will not
+ *                    be greater than nb_samples, and will only be less than
+ *                    nb_samples if av_audio_fifo_size is less than nb_samples.
+ */
+int av_audio_fifo_peek_at(AVAudioFifo *af, void **data, int nb_samples, int offset);
+
 /**
  * Read data from an AVAudioFifo.
  *