@@ -640,7 +640,8 @@ list of the supported standards, use the @option{list_standards}

 option.

 @item channel

-Set the input channel number. Default to 0.

+Set the input channel number. Default to -1, which means using the

+previously selected channel.

 @item video_size

 Set the video frame size. The argument must be a string in the form

@@ -894,14 +894,24 @@ static int v4l2_read_header(AVFormatContext *s1)

     if (s->fd < 0)

         return s->fd;

-    /* set tv video input */

-    av_log(s1, AV_LOG_DEBUG, "Selecting input_channel: %d\n", s->channel);

-    if (v4l2_ioctl(s->fd, VIDIOC_S_INPUT, &s->channel) < 0) {

-        res = AVERROR(errno);

-        av_log(s1, AV_LOG_ERROR, "ioctl(VIDIOC_S_INPUT): %s\n", av_err2str(res));

-        return res;

+    if (s->channel != -1) {

+        /* set video input */

+        av_log(s1, AV_LOG_DEBUG, "Selecting input_channel: %d\n", s->channel);

+        if (v4l2_ioctl(s->fd, VIDIOC_S_INPUT, &s->channel) < 0) {

+            res = AVERROR(errno);

+            av_log(s1, AV_LOG_ERROR, "ioctl(VIDIOC_S_INPUT): %s\n", av_err2str(res));

+            return res;

+        }

+    } else {

+        /* get current video input */

+        if (v4l2_ioctl(s->fd, VIDIOC_G_INPUT, &s->channel) < 0) {

+            res = AVERROR(errno);

+            av_log(s1, AV_LOG_ERROR, "ioctl(VIDIOC_G_INPUT): %s\n", av_err2str(res));

+            return res;

+        }

     }

+    /* enum input */

     input.index = s->channel;

     if (v4l2_ioctl(s->fd, VIDIOC_ENUMINPUT, &input) < 0) {

         res = AVERROR(errno);

@@ -909,7 +919,7 @@ static int v4l2_read_header(AVFormatContext *s1)

         return res;

     }

     s->std_id = input.std;

-    av_log(s1, AV_LOG_DEBUG, "input_channel: %d, input_name: %s\n",

+    av_log(s1, AV_LOG_DEBUG, "Current input_channel: %d, input_name: %s\n",

            s->channel, input.name);

     if (s->list_format) {

@@ -1045,7 +1055,7 @@ static int v4l2_read_close(AVFormatContext *s1)

 static const AVOption options[] = {

     { "standard",     "set TV standard, used only by analog frame grabber",       OFFSET(standard),     AV_OPT_TYPE_STRING, {.str = NULL }, 0, 0,       DEC },

-    { "channel",      "set TV channel, used only by frame grabber",               OFFSET(channel),      AV_OPT_TYPE_INT,    {.i64 = 0 },    0, INT_MAX, DEC },

+    { "channel",      "set TV channel, used only by frame grabber",               OFFSET(channel),      AV_OPT_TYPE_INT,    {.i64 = -1 },  -1, INT_MAX, DEC },

     { "video_size",   "set frame size",                                           OFFSET(width),        AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL},  0, 0,   DEC },

     { "pixel_format", "set preferred pixel format",                               OFFSET(pixel_format), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       DEC },

     { "input_format", "set preferred pixel format (for raw video) or codec name", OFFSET(pixel_format), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       DEC },