lavdev: improve feedback in case of invalid frame rate/size

Show the invalid string in the error message.

While at it also prefer "Could not" over "Couldn't", plain forms are
preferred over contractions (simplify readability, especially for non
English-savvy people).

Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavdevice/bktr.c

@@ -263,7 +263,7 @@ static int grab_read_header(AVFormatContext *s1, AVFormatParameters *ap)
 #endif
 
     if ((ret = av_parse_video_size(&width, &height, s->video_size)) < 0) {
-        av_log(s1, AV_LOG_ERROR, "Couldn't parse video size.\n");
+        av_log(s1, AV_LOG_ERROR, "Could not parse video size '%s'.\n", s->video_size);
         goto out;
     }
 
@@ -278,7 +278,7 @@ static int grab_read_header(AVFormatContext *s1, AVFormatParameters *ap)
             goto out;
         }
     if ((ret = av_parse_video_rate(&framerate, s->framerate)) < 0) {
-        av_log(s1, AV_LOG_ERROR, "Couldn't parse framerate.\n");
+        av_log(s1, AV_LOG_ERROR, "Could not parse framerate '%s'.\n", s->framerate);
         goto out;
     }
 #if FF_API_FORMAT_PARAMETERS

libavdevice/fbdev.c

@@ -104,7 +104,7 @@ av_cold static int fbdev_read_header(AVFormatContext *avctx,
 
     ret = av_parse_video_rate(&fbdev->framerate_q, fbdev->framerate);
     if (ret < 0) {
-        av_log(avctx, AV_LOG_ERROR, "Couldn't parse framerate.\n");
+        av_log(avctx, AV_LOG_ERROR, "Could not parse framerate '%s'.\n", fbdev->framerate);
         return ret;
     }
 #if FF_API_FORMAT_PARAMETERS

libavdevice/libdc1394.c

@@ -134,11 +134,11 @@ static inline int dc1394_read_common(AVFormatContext *c, AVFormatParameters *ap,
     }
 
     if ((ret = av_parse_video_size(&width, &height, dc1394->video_size)) < 0) {
-        av_log(c, AV_LOG_ERROR, "Couldn't parse video size.\n");
+        av_log(c, AV_LOG_ERROR, "Could not parse video size '%s'.\n", dc1394->video_size);
         goto out;
     }
     if ((ret = av_parse_video_rate(&framerate, dc1394->framerate)) < 0) {
-        av_log(c, AV_LOG_ERROR, "Couldn't parse framerate.\n");
+        av_log(c, AV_LOG_ERROR, "Could not parse framerate '%s'.\n", dc1394->framerate);
         goto out;
     }
 #if FF_API_FORMAT_PARAMETERS

libavdevice/v4l2.c

@@ -460,7 +460,7 @@ static int v4l2_set_parameters(AVFormatContext *s1, AVFormatParameters *ap)
     streamparm.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 
     if (s->framerate && (ret = av_parse_video_rate(&framerate_q, s->framerate)) < 0) {
-        av_log(s1, AV_LOG_ERROR, "Couldn't parse framerate.\n");
+        av_log(s1, AV_LOG_ERROR, "Could not parse framerate '%s'.\n", s->framerate);
         return ret;
     }
 #if FF_API_FORMAT_PARAMETERS
@@ -601,7 +601,7 @@ static int v4l2_read_header(AVFormatContext *s1, AVFormatParameters *ap)
     av_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
 
     if (s->video_size && (res = av_parse_video_size(&s->width, &s->height, s->video_size)) < 0) {
-        av_log(s1, AV_LOG_ERROR, "Couldn't parse video size.\n");
+        av_log(s1, AV_LOG_ERROR, "Could not parse video size '%s'.\n", s->video_size);
         goto out;
     }
     if (s->pixel_format && (pix_fmt = av_get_pix_fmt(s->pixel_format)) == PIX_FMT_NONE) {