@@ -586,14 +586,6 @@ static int v4l2_read_header(AVFormatContext *s1, AVFormatParameters *ap)

     uint32_t desired_format, capabilities;

     enum CodecID codec_id;

-    if (ap->width <= 0 || ap->height <= 0) {

-        av_log(s1, AV_LOG_ERROR, "Wrong size (%dx%d)\n", ap->width, ap->height);

-        return AVERROR(EINVAL);

-    }

-

-    if(avcodec_check_dimensions(s1, ap->width, ap->height) < 0)

-        return AVERROR(EINVAL);

-

     st = av_new_stream(s1, 0);

     if (!st) {

         return AVERROR(ENOMEM);

@@ -610,7 +602,25 @@ static int v4l2_read_header(AVFormatContext *s1, AVFormatParameters *ap)

     }

     av_log(s1, AV_LOG_INFO, "[%d]Capabilities: %x\n", s->fd, capabilities);

+    if (!s->width && !s->height) {

+        struct v4l2_format fmt;

+

+        av_log(s1, AV_LOG_INFO, "Size value (%dx%d) unspecified, querying the device for the current settings\n",

+               s->width, s->height);

+        fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

+        if (ioctl(s->fd, VIDIOC_G_FMT, &fmt) < 0) {

+            av_log(s1, AV_LOG_ERROR, "ioctl(VIDIOC_G_FMT): %s\n", strerror(errno));

+            return AVERROR(errno);

+        }

+        s->width  = fmt.fmt.pix.width;

+        s->height = fmt.fmt.pix.height;

+        av_log(s1, AV_LOG_INFO, "Setting size to value %dx%d\n", s->width, s->height);

+    }

+

     desired_format = device_try_init(s1, ap, &s->width, &s->height, &codec_id);

+    if (avcodec_check_dimensions(s1, s->width, s->height) < 0)

+        return AVERROR(EINVAL);

+

     if (desired_format == 0) {

         av_log(s1, AV_LOG_ERROR, "Cannot find a proper format for "

                "codec_id %d, pix_fmt %d.\n", s1->video_codec_id, ap->pix_fmt);