lavc: add trailing_padding to AVCodecContext to match AVCodecParameters.

Shows encoder delay/padding in the stream summary if they are set.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

doc/APIchanges

@@ -15,6 +15,10 @@ libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2016-08-15 - xxxxxxx - lavc 57.53.100 - avcodec.h
+  Add trailing_padding to AVCodecContext to match the corresponding
+  field in AVCodecParameters.
+
 2016-08-04 - xxxxxxx - lavf 57.46.100 - avformat.h
   Add av_get_frame_filename2()
 

libavcodec/avcodec.h

@@ -3524,6 +3524,17 @@ typedef struct AVCodecContext {
 #define FF_SUB_TEXT_FMT_ASS_WITH_TIMINGS 1
 #endif
 
+    /**
+     * Audio only. The amount of padding (in samples) appended by the encoder to
+     * the end of the audio. I.e. this number of decoded samples must be
+     * discarded by the caller from the end of the stream to get the original
+     * audio without any trailing padding.
+     *
+     * - decoding: unused
+     * - encoding: unused
+     */
+    int trailing_padding;
+
 } AVCodecContext;
 
 AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);

libavcodec/utils.c

@@ -3258,6 +3258,10 @@ void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode)
             && enc->bits_per_raw_sample != av_get_bytes_per_sample(enc->sample_fmt) * 8)
             snprintf(buf + strlen(buf), buf_size - strlen(buf),
                      " (%d bit)", enc->bits_per_raw_sample);
+        if (enc->initial_padding || enc->trailing_padding) {
+            snprintf(buf + strlen(buf), buf_size - strlen(buf),
+                     ", delay %d, padding %d", enc->initial_padding, enc->trailing_padding);
+        }
         break;
     case AVMEDIA_TYPE_DATA:
         if (av_log_get_level() >= AV_LOG_DEBUG) {
@@ -4110,6 +4114,7 @@ int avcodec_parameters_from_context(AVCodecParameters *par,
         par->block_align      = codec->block_align;
         par->frame_size       = codec->frame_size;
         par->initial_padding  = codec->initial_padding;
+        par->trailing_padding = codec->trailing_padding;
         par->seek_preroll     = codec->seek_preroll;
         break;
     case AVMEDIA_TYPE_SUBTITLE:
@@ -4165,6 +4170,7 @@ int avcodec_parameters_to_context(AVCodecContext *codec,
         codec->frame_size       = par->frame_size;
         codec->delay            =
         codec->initial_padding  = par->initial_padding;
+        codec->trailing_padding = par->trailing_padding;
         codec->seek_preroll     = par->seek_preroll;
         break;
     case AVMEDIA_TYPE_SUBTITLE:

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  57
-#define LIBAVCODEC_VERSION_MINOR  52
+#define LIBAVCODEC_VERSION_MINOR  53
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \