ffmpeg: make -aspect work with -vcodec copy.

doc/ffmpeg.texi

@@ -468,6 +468,10 @@ form @var{num}:@var{den}, where @var{num} and @var{den} are the
 numerator and denominator of the aspect ratio. For example "4:3",
 "16:9", "1.3333", and "1.7777" are valid argument values.
 
+If used together with @option{-vcodec copy}, it will affect the aspect ratio
+stored at container level, but not the aspect ratio stored in encoded
+frames, if it exists.
+
 @item -vn (@emph{output})
 Disable video recording.
 

ffmpeg.c

@@ -2224,7 +2224,14 @@ static int transcode_init(void)
                 codec->width              = icodec->width;
                 codec->height             = icodec->height;
                 codec->has_b_frames       = icodec->has_b_frames;
-                if (!codec->sample_aspect_ratio.num) {
+                if (ost->frame_aspect_ratio.num) { // overridden by the -aspect cli option
+                    codec->sample_aspect_ratio   =
+                    ost->st->sample_aspect_ratio =
+                        av_mul_q(ost->frame_aspect_ratio,
+                                 (AVRational){ codec->height, codec->width });
+                    av_log(NULL, AV_LOG_WARNING, "Overriding aspect ratio "
+                           "with stream copy may produce invalid files\n");
+                } else 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 :

ffmpeg_opt.c

@@ -1168,7 +1168,7 @@ static OutputStream *new_video_stream(OptionsContext *o, AVFormatContext *oc, in
     AVStream *st;
     OutputStream *ost;
     AVCodecContext *video_enc;
-    char *frame_rate = NULL;
+    char *frame_rate = NULL, *frame_aspect_ratio = NULL;
 
     ost = new_output_stream(o, oc, AVMEDIA_TYPE_VIDEO, source_index);
     st  = ost->st;
@@ -1180,10 +1180,21 @@ static OutputStream *new_video_stream(OptionsContext *o, AVFormatContext *oc, in
         exit(1);
     }
 
+    MATCH_PER_STREAM_OPT(frame_aspect_ratios, str, frame_aspect_ratio, oc, st);
+    if (frame_aspect_ratio) {
+        AVRational q;
+        if (av_parse_ratio(&q, frame_aspect_ratio, 255, 0, NULL) < 0 ||
+            q.num <= 0 || q.den <= 0) {
+            av_log(NULL, AV_LOG_FATAL, "Invalid aspect ratio: %s\n", frame_aspect_ratio);
+            exit(1);
+        }
+        ost->frame_aspect_ratio = q;
+    }
+
     if (!ost->stream_copy) {
         const char *p = NULL;
         char *frame_size = NULL;
-        char *frame_aspect_ratio = NULL, *frame_pix_fmt = NULL;
+        char *frame_pix_fmt = NULL;
         char *intra_matrix = NULL, *inter_matrix = NULL;
         int do_pass = 0;
         int i;
@@ -1194,17 +1205,6 @@ static OutputStream *new_video_stream(OptionsContext *o, AVFormatContext *oc, in
             exit(1);
         }
 
-        MATCH_PER_STREAM_OPT(frame_aspect_ratios, str, frame_aspect_ratio, oc, st);
-        if (frame_aspect_ratio) {
-            AVRational q;
-            if (av_parse_ratio(&q, frame_aspect_ratio, 255, 0, NULL) < 0 ||
-                q.num <= 0 || q.den <= 0) {
-                av_log(NULL, AV_LOG_FATAL, "Invalid aspect ratio: %s\n", frame_aspect_ratio);
-                exit(1);
-            }
-            ost->frame_aspect_ratio = q;
-        }
-
         video_enc->bits_per_raw_sample = frame_bits_per_raw_sample;
         MATCH_PER_STREAM_OPT(frame_pix_fmts, str, frame_pix_fmt, oc, st);
         if (frame_pix_fmt && *frame_pix_fmt == '+') {