[FFmpeg-devel] [PATCH] avcodec/noise_bsf: Add keyframes option.

[Josh Allmann]

---
 doc/bitstream_filters.texi |  5 +++++
 libavcodec/noise_bsf.c     | 12 ++++++++++++
 libavcodec/version.h       |  2 +-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index cfd81fa12d..a9f17f32ec 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -399,6 +399,11 @@ every byte is modified.
 A numeral string, whose value is related to how often packets will be dropped.
 Therefore, values below or equal to 0 are forbidden, and the lower the more
 frequent packets will be dropped, with 1 meaning every packet is dropped.
+ at item keyframes
+A numeral string, whose value indicates the number of keyframe packets that
+will be dropped from the beginning of the stream. This option will not add
+noise to the source data. If used with stream copy, then -copyinkf should
+be added to the output options as well.
 @end table
 
 The following example applies the modification to every byte but does not drop
diff --git a/libavcodec/noise_bsf.c b/libavcodec/noise_bsf.c
index 84b94032ad..363ea4fc71 100644
--- a/libavcodec/noise_bsf.c
+++ b/libavcodec/noise_bsf.c
@@ -32,6 +32,7 @@ typedef struct NoiseContext {
     const AVClass *class;
     int amount;
     int dropamount;
+    int keyframes;
     unsigned int state;
 } NoiseContext;
 
@@ -49,6 +50,13 @@ static int noise(AVBSFContext *ctx, AVPacket *out)
     if (ret < 0)
         return ret;
 
+    if (s->keyframes > 0 && in->flags & AV_PKT_FLAG_KEY) {
+      s->keyframes--;
+      if (!s->keyframes) s->keyframes = -1;
+      av_packet_free(&in);
+      return AVERROR(EAGAIN);
+    }
+
     if (s->dropamount > 0 && s->state % s->dropamount == 0) {
         s->state++;
         av_packet_free(&in);
@@ -65,6 +73,9 @@ static int noise(AVBSFContext *ctx, AVPacket *out)
 
     memcpy(out->data, in->data, in->size);
 
+    if (s->keyframes)
+      return ret;
+
     for (i = 0; i < out->size; i++) {
         s->state += out->data[i] + 1;
         if (s->state % amount == 0)
@@ -81,6 +92,7 @@ fail:
 static const AVOption options[] = {
     { "amount", NULL, OFFSET(amount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX },
     { "dropamount", NULL, OFFSET(dropamount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX },
+    { "keyframes", NULL, OFFSET(keyframes), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX },
     { NULL },
 };
 
diff --git a/libavcodec/version.h b/libavcodec/version.h
index ca18ce6e8b..1e84410d68 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -29,7 +29,7 @@
 
 #define LIBAVCODEC_VERSION_MAJOR  58
 #define LIBAVCODEC_VERSION_MINOR  13
-#define LIBAVCODEC_VERSION_MICRO 100
+#define LIBAVCODEC_VERSION_MICRO 101
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \
-- 
2.14.2