[PATCH 01/10] Add a time_base field to AVFilterLink.

[Stefano Sabatini]

This is required for allowing a filter to use a time base different
from AV_TIME_BASE_Q, as it was previously assumed.
---
 libavfilter/avfilter.c |    4 ++++
 libavfilter/avfilter.h |   13 ++++++++++++-
 libavfilter/defaults.c |   14 +++++++++++++-
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index ea6f9fe..d528455 100644
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -23,6 +23,7 @@
 
 #include "libavcodec/audioconvert.c"
 #include "libavutil/pixdesc.h"
+#include "libavutil/rational.h"
 #include "libavcore/imgutils.h"
 #include "avfilter.h"
 #include "internal.h"
@@ -179,6 +180,9 @@ int avfilter_config_links(AVFilterContext *filter)
             if (config_link(link))
                 return -1;
 
+            if (link->time_base.num == 0 && link->time_base.den == 0)
+                link->time_base = AV_TIME_BASE_Q;
+
             if ((config_link = link->dstpad->config_props))
                 if (config_link(link))
                     return -1;
diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h
index 20901a3..9762960 100644
--- a/libavfilter/avfilter.h
+++ b/libavfilter/avfilter.h
@@ -127,7 +127,12 @@ typedef struct AVFilterBufferRef {
     int linesize[8];            ///< number of bytes per line
     int format;                 ///< media format
 
-    int64_t pts;                ///< presentation timestamp in units of 1/AV_TIME_BASE
+    /**
+     * presentation timestamp. The time unit may change during
+     * filtering, as it is specified in the link and the filter code
+     * may need to rescale the PTS accordingly.
+     */
+    int64_t pts;
     int64_t pos;                ///< byte position in stream, -1 if unknown
 
     int perms;                  ///< permissions, see the AV_PERM_* flags
@@ -598,6 +603,12 @@ struct AVFilterLink {
 
     AVFilterBufferRef *cur_buf;
     AVFilterBufferRef *out_buf;
+
+    /**
+     * Define the time base used by the PTS of the frames/samples
+     * which will pass through this link.
+     */
+    AVRational time_base;
 };
 
 /**
diff --git a/libavfilter/defaults.c b/libavfilter/defaults.c
index cb9ed19..838ed99 100644
--- a/libavfilter/defaults.c
+++ b/libavfilter/defaults.c
@@ -169,6 +169,8 @@ void avfilter_default_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
     if (out) {
         out->out_buf      = avfilter_get_video_buffer(out, AV_PERM_WRITE, out->w, out->h);
         avfilter_copy_buffer_ref_props(out->out_buf, picref);
+        if (av_cmp_q(link->time_base, out->time_base))
+            out->out_buf->pts = av_rescale_q(picref->pts, link->time_base, out->time_base);
         avfilter_start_frame(out, avfilter_ref_buffer(out->out_buf, ~0));
     }
 }
@@ -235,6 +237,7 @@ int avfilter_default_config_output_link(AVFilterLink *link)
         if (link->type == AVMEDIA_TYPE_VIDEO) {
             link->w = link->src->inputs[0]->w;
             link->h = link->src->inputs[0]->h;
+            link->time_base = link->src->inputs[0]->time_base;
         } else if (link->type == AVMEDIA_TYPE_AUDIO) {
             link->channel_layout = link->src->inputs[0]->channel_layout;
             link->sample_rate    = link->src->inputs[0]->sample_rate;
@@ -292,7 +295,16 @@ int avfilter_default_query_formats(AVFilterContext *ctx)
 
 void avfilter_null_start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
 {
-    avfilter_start_frame(link->dst->outputs[0], picref);
+    AVFilterLink *outlink = link->dst->outputs[0];
+    AVFilterBufferRef *picref2 = picref;
+
+    if (av_cmp_q(link->time_base, outlink->time_base)) {
+        picref2 = avfilter_ref_buffer(picref, ~0);
+        avfilter_unref_buffer(picref);
+        picref2->pts = av_rescale_q(picref->pts, link->time_base, outlink->time_base);
+    }
+
+    avfilter_start_frame(outlink, picref2);
 }
 
 void avfilter_null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
-- 
1.7.1


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