fftools/ffmpeg_filter: move most of -apad logic to the muxer

The decision whether -apad actually does anything is made based on muxer
properties, and so more properly belongs there. Filtering code only
receives the result.

fftools/ffmpeg.h

@@ -320,6 +320,8 @@ typedef struct OutputFilter {
      * this stores the output linklabel, if any */
     uint8_t             *linklabel;
 
+    char                *apad;
+
     enum AVMediaType     type;
 
     atomic_uint_least64_t nb_frames_dup;
@@ -581,7 +583,6 @@ typedef struct OutputStream {
     OutputFilter *filter;
 
     AVDictionary *encoder_opts;
-    char *apad;
 
     char *attachment_filename;
 

fftools/ffmpeg_filter.c

@@ -969,6 +969,7 @@ void fg_free(FilterGraph **pfg)
 
         av_freep(&ofilter->linklabel);
         av_freep(&ofilter->name);
+        av_freep(&ofilter->apad);
         av_freep(&ofp->name);
         av_channel_layout_uninit(&ofp->ch_layout);
         av_freep(&fg->outputs[j]);
@@ -1430,8 +1431,6 @@ static int configure_output_audio_filter(FilterGraph *fg, AVFilterGraph *graph,
                                          OutputFilter *ofilter, AVFilterInOut *out)
 {
     OutputFilterPriv *ofp = ofp_from_ofilter(ofilter);
-    OutputStream *ost = ofilter->ost;
-    OutputFile    *of = ost->file;
     AVFilterContext *last_filter = out->filter_ctx;
     int pad_idx = out->pad_idx;
     AVBPrint args;
@@ -1493,17 +1492,8 @@ static int configure_output_audio_filter(FilterGraph *fg, AVFilterGraph *graph,
         pad_idx = 0;
     }
 
-    if (ost->apad && of->shortest) {
-        int i;
-
-        for (i = 0; i < of->nb_streams; i++)
-            if (of->streams[i]->st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
-                break;
-
-        if (i < of->nb_streams) {
-            AUTO_INSERT_FILTER("-apad", "apad", ost->apad);
-        }
-    }
+    if (ofilter->apad)
+        AUTO_INSERT_FILTER("-apad", "apad", ofilter->apad);
 
     snprintf(name, sizeof(name), "trim for output %s", ofp->name);
     ret = insert_trim(ofp->trim_start_us, ofp->trim_duration_us,

fftools/ffmpeg_mux.c

@@ -815,7 +815,6 @@ static void ost_free(OutputStream **post)
     av_expr_free(ost->kf.pexpr);
 
     av_freep(&ost->logfile_prefix);
-    av_freep(&ost->apad);
 
     av_freep(&ost->attachment_filename);
 

fftools/ffmpeg_mux.h

@@ -78,6 +78,8 @@ typedef struct MuxStream {
 #if FFMPEG_OPT_VSYNC_DROP
     int             ts_drop;
 #endif
+
+    char           *apad;
 } MuxStream;
 
 typedef struct Muxer {

fftools/ffmpeg_mux_init.c

@@ -828,6 +828,7 @@ static int new_stream_video(Muxer *mux, const OptionsContext *o,
 static int new_stream_audio(Muxer *mux, const OptionsContext *o,
                             OutputStream *ost)
 {
+    MuxStream *ms = ms_from_ost(ost);
     AVFormatContext *oc = mux->fc;
     AVStream *st = ost->st;
 
@@ -836,7 +837,6 @@ static int new_stream_audio(Muxer *mux, const OptionsContext *o,
         int channels = 0;
         char *layout = NULL;
         char *sample_fmt = NULL;
-        const char *apad = NULL;
 
         MATCH_PER_STREAM_OPT(audio_channels, i, channels, oc, st);
         if (channels) {
@@ -859,12 +859,7 @@ static int new_stream_audio(Muxer *mux, const OptionsContext *o,
 
         MATCH_PER_STREAM_OPT(audio_sample_rate, i, audio_enc->sample_rate, oc, st);
 
-        MATCH_PER_STREAM_OPT(apad, str, apad, oc, st);
-        if (apad) {
-            ost->apad = av_strdup(apad);
-            if (!ost->apad)
-                return AVERROR(ENOMEM);
-        }
+        MATCH_PER_STREAM_OPT(apad, str, ms->apad, oc, st);
     }
 
     return 0;
@@ -1890,6 +1885,33 @@ static int create_streams(Muxer *mux, const OptionsContext *o)
         }
     }
 
+    // handle -apad
+    if (mux->of.shortest) {
+        int have_video = 0;
+
+        for (unsigned i = 0; i < mux->of.nb_streams; i++)
+            if (mux->of.streams[i]->type == AVMEDIA_TYPE_VIDEO) {
+                have_video = 1;
+                break;
+            }
+
+        for (unsigned i = 0; have_video && i < mux->of.nb_streams; i++) {
+            MuxStream         *ms = ms_from_ost(mux->of.streams[i]);
+            OutputFilter *ofilter = ms->ost.filter;
+
+            if (ms->ost.type != AVMEDIA_TYPE_AUDIO || !ms->apad || !ofilter)
+                continue;
+
+            ofilter->apad = av_strdup(ms->apad);
+            if (!ofilter->apad)
+                return AVERROR(ENOMEM);
+        }
+    }
+    for (unsigned i = 0; i < mux->of.nb_streams; i++) {
+        MuxStream *ms = ms_from_ost(mux->of.streams[i]);
+        ms->apad = NULL;
+    }
+
     if (!oc->nb_streams && !(oc->oformat->flags & AVFMT_NOSTREAMS)) {
         av_dump_format(oc, nb_output_files - 1, oc->url, 1);
         av_log(mux, AV_LOG_ERROR, "Output file does not contain any stream\n");