On Friday 27 March 2015 02:45:22 pm Michael Niedermayer wrote:
> On Fri, Mar 27, 2015 at 08:07:23AM +0000, Carl Eugen Hoyos wrote:
> > Michael Niedermayer <michaelni <at> gmx.at> writes:
> > > On Fri, Mar 27, 2015 at 12:21:00AM +0000, Carl Eugen Hoyos wrote:
> > > > Michael Niedermayer <michaelni <at> gmx.at> writes:
> > > > > iam not sure the default of 6 seconds is safe
> > > >
> > > > What would be a sensible default max_delay?
> > >
> > > for this file simply considering 0xFFFF as 0 would work
> > > and would so i think only replacing that would be the
> > > least change needed
> >
> > I did not find any specification that suggests to do this
> > (but many pages were 0xFFFF is explicitely mentioned as
> > allowing for maximum delay).
>
> one could add a option like max_delay which is then used in place
> of 0xFFFF, conforming to the spec if taken litterally
I attached a new version of the patch that does not change the
current behaviour but gives users a chance to play long gifs in
real-time.
> The only reason i can imagine a file would be using the "max delay"
> would be to wait for user input before displaying the next frame
> i thought thats not the reason for this file though but i might be
> wrong
Imo, the main reason to use "max delay" is if the creator wants a
frame to be shown for more than ten minutes.
Carl Eugen
diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index 11dfe1b..289787d 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -205,6 +205,11 @@ It accepts the following options:
Set the minimum valid delay between frames in hundredths of seconds.
Range is 0 to 6000. Default value is 2.
+@item max_gif_delay
+Set the maximum valid delay between frames in hundredth of seconds.
+Range is 0 to 65535. Default value is 65535, the maximum value
+allowed by the specification.
+
@item default_delay
Set the default delay between frames in hundredths of seconds.
Range is 0 to 6000. Default value is 10.
diff --git a/libavformat/gifdec.c b/libavformat/gifdec.c
index 7db5a27..bb4c6ec 100644
--- a/libavformat/gifdec.c
+++ b/libavformat/gifdec.c
@@ -43,6 +43,7 @@ typedef struct GIFDemuxContext {
* invalid and set to value of default_delay.
*/
int min_delay;
+ int max_delay;
int default_delay;
/**
@@ -159,6 +160,7 @@ static int gif_read_ext(AVFormatContext *s)
if (gdc->delay < gdc->min_delay)
gdc->delay = gdc->default_delay;
+ gdc->delay = FFMIN(gdc->delay, gdc->max_delay);
/* skip the rest of the Graphic Control Extension block */
if ((ret = avio_skip(pb, sb_size - 3)) < 0 )
@@ -309,6 +311,7 @@ resync:
static const AVOption options[] = {
{ "min_delay" , "minimum valid delay between frames (in hundredths of
second)", offsetof(GIFDemuxContext, min_delay) , AV_OPT_TYPE_INT, {.i64 =
GIF_MIN_DELAY} , 0, 100 * 60, AV_OPT_FLAG_DECODING_PARAM },
+ { "max_gif_delay", "maximum valid delay between frames (in hundredths of
seconds)", offsetof(GIFDemuxContext, max_delay) , AV_OPT_TYPE_INT, {.i64 =
65535} , 0, 65535 , AV_OPT_FLAG_DECODING_PARAM },
{ "default_delay", "default delay between frames (in hundredths of
second)" , offsetof(GIFDemuxContext, default_delay), AV_OPT_TYPE_INT,
{.i64 = GIF_DEFAULT_DELAY}, 0, 100 * 60, AV_OPT_FLAG_DECODING_PARAM },
{ "ignore_loop" , "ignore loop setting (netscape extension)"
, offsetof(GIFDemuxContext, ignore_loop) , AV_OPT_TYPE_INT, {.i64 = 1}
, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
{ NULL },
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