ffmpeg: fix -aspect cli option

Redesign the way -aspect option is handled. This is done by making
ffmpeg read the sample aspect ratio set in the corresponding input
stream by default, and overriding it using the value specified by
-aspect.

If the output display aspect ratio is specified with -aspect, it is
set at the end of the filterchain, thus overriding the value set by
filters in the filterchain.

This implementation is more robust, since does not modify the
filterchain description (which was creating potential syntax errors).

(Cherry-pick abf8342aa9)

Another aspect ratio fix try. This leaves the setdar addition at the end
(preferred by people).

(Cherry-pick e7c7b0d000)

ffmpeg.c

@@ -274,6 +274,8 @@ typedef struct AVOutputStream {
     int resample_width;
     int resample_pix_fmt;
 
+    float frame_aspect_ratio;
+
     /* forced key frames */
     int64_t *forced_kf_pts;
     int forced_kf_count;
@@ -411,6 +413,8 @@ static int configure_video_filters(AVInputStream *ist, AVOutputStream *ost)
     codec->width  = ost->output_video_filter->inputs[0]->w;
     codec->height = ost->output_video_filter->inputs[0]->h;
     codec->sample_aspect_ratio = ost->st->sample_aspect_ratio =
+        ost->frame_aspect_ratio ? // overriden by the -aspect cli option
+        av_d2q(ost->frame_aspect_ratio*codec->height/codec->width, 255) :
         ost->output_video_filter->inputs[0]->sample_aspect_ratio;
 
     return 0;
@@ -1623,7 +1627,7 @@ static int output_packet(AVInputStream *ist, int ist_index,
                             break;
                         case AVMEDIA_TYPE_VIDEO:
 #if CONFIG_AVFILTER
-                            if (ost->picref->video)
+                            if (ost->picref->video && !ost->frame_aspect_ratio)
                                 ost->st->codec->sample_aspect_ratio = ost->picref->video->pixel_aspect;
 #endif
                             do_video_out(os, ost, ist, &picture, &frame_size);
@@ -2132,6 +2136,13 @@ static int transcode(AVFormatContext **output_files,
                 codec->width = icodec->width;
                 codec->height = icodec->height;
                 codec->has_b_frames = icodec->has_b_frames;
+                if (!codec->sample_aspect_ratio.num) {
+                    codec->sample_aspect_ratio =
+                    ost->st->sample_aspect_ratio =
+                        ist->st->sample_aspect_ratio.num ? ist->st->sample_aspect_ratio :
+                        ist->st->codec->sample_aspect_ratio.num ?
+                        ist->st->codec->sample_aspect_ratio : (AVRational){0, 1};
+                }
                 break;
             case AVMEDIA_TYPE_SUBTITLE:
                 codec->width = icodec->width;
@@ -3220,11 +3231,6 @@ static void opt_input_file(const char *filename)
             set_context_opts(dec, avcodec_opts[AVMEDIA_TYPE_VIDEO], AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM, input_codecs[nb_input_codecs-1]);
             frame_height = dec->height;
             frame_width  = dec->width;
-            if(ic->streams[i]->sample_aspect_ratio.num)
-                frame_aspect_ratio=av_q2d(ic->streams[i]->sample_aspect_ratio);
-            else
-                frame_aspect_ratio=av_q2d(dec->sample_aspect_ratio);
-            frame_aspect_ratio *= (float) dec->width / dec->height;
             frame_pix_fmt = dec->pix_fmt;
             rfps      = ic->streams[i]->r_frame_rate.num;
             rfps_base = ic->streams[i]->r_frame_rate.den;
@@ -3337,7 +3343,6 @@ static void new_video_stream(AVFormatContext *oc, int file_idx)
     AVCodecContext *video_enc;
     enum CodecID codec_id = CODEC_ID_NONE;
     AVCodec *codec= NULL;
-    int i;
 
     st = av_new_stream(oc, oc->nb_streams < nb_streamid_map ? streamid_map[oc->nb_streams] : 0);
     if (!st) {
@@ -3358,14 +3363,9 @@ static void new_video_stream(AVFormatContext *oc, int file_idx)
             codec = avcodec_find_encoder(codec_id);
         }
 
+        ost->frame_aspect_ratio = frame_aspect_ratio;
+        frame_aspect_ratio = 0;
 #if CONFIG_AVFILTER
-        if (frame_aspect_ratio > 0){
-            i = vfilters ? strlen(vfilters) : 0;
-            vfilters = av_realloc(vfilters, i+100);
-            snprintf(vfilters+i, i+100, "%csetdar=%f\n", i?',':' ', frame_aspect_ratio);
-            frame_aspect_ratio=0;
-        }
-
         ost->avfilter= vfilters;
         vfilters = NULL;
 #endif
@@ -3412,7 +3412,6 @@ static void new_video_stream(AVFormatContext *oc, int file_idx)
 
         video_enc->width = frame_width;
         video_enc->height = frame_height;
-        video_enc->sample_aspect_ratio = av_d2q(frame_aspect_ratio*video_enc->height/video_enc->width, 255);
         video_enc->pix_fmt = frame_pix_fmt;
         st->sample_aspect_ratio = video_enc->sample_aspect_ratio;