bsf: add a flushing mechanism to AVBSFContext

Meant to reset the internal bsf state without the need to reinitialize it.
Signed-off-by: James Almer <jamrial@gmail.com>

doc/APIchanges

@@ -13,6 +13,9 @@ libavutil:     2017-03-23
 
 API changes, most recent first:
 
+2018-xx-xx - xxxxxxx - lavc 58.10.0 - avcodec.h
+  Add av_bsf_flush().
+
 2018-02-xx - xxxxxxx - lavfi 7.1.0 - avfilter.h
   Add AVFilterContext.extra_hw_frames.
 

libavcodec/avcodec.h

@@ -4927,6 +4927,7 @@ typedef struct AVBitStreamFilter {
     int (*init)(AVBSFContext *ctx);
     int (*filter)(AVBSFContext *ctx, AVPacket *pkt);
     void (*close)(AVBSFContext *ctx);
+    void (*flush)(AVBSFContext *ctx);
 } AVBitStreamFilter;
 
 #if FF_API_OLD_BSF
@@ -5029,6 +5030,11 @@ int av_bsf_send_packet(AVBSFContext *ctx, AVPacket *pkt);
  */
 int av_bsf_receive_packet(AVBSFContext *ctx, AVPacket *pkt);
 
+/**
+ * Reset the internal bitstream filter state / flush internal buffers.
+ */
+void av_bsf_flush(AVBSFContext *ctx);
+
 /**
  * Free a bitstream filter context and everything associated with it; write NULL
  * into the supplied pointer.

libavcodec/bsf.c

@@ -170,6 +170,16 @@ int av_bsf_init(AVBSFContext *ctx)
     return 0;
 }
 
+void av_bsf_flush(AVBSFContext *ctx)
+{
+    ctx->internal->eof = 0;
+
+    av_packet_unref(ctx->internal->buffer_pkt);
+
+    if (ctx->filter->flush)
+        ctx->filter->flush(ctx);
+}
+
 int av_bsf_send_packet(AVBSFContext *ctx, AVPacket *pkt)
 {
     if (!pkt || !pkt->data) {

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 58
-#define LIBAVCODEC_VERSION_MINOR  9
+#define LIBAVCODEC_VERSION_MINOR 10
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \