Re: [FFmpeg-devel] [PATCH] lavf/mxfdec: fix seeking before the first keyframe

[Marton Balint]

On Mon, 7 Dec 2015, Tomas Härdin wrote:


On Sat, 2015-11-28 at 02:56 +0100, Marton Balint wrote:

Regression since 53f2ef2c4afb1d49a679dea9163cb0e4671f3117.
Fixes ticket #5017.

Signed-off-by: Marton Balint 
---
 libavformat/mxfdec.c | 10 ++
 1 file changed, 10 insertions(+)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 429f46a..926d2a3 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -3181,6 +3181,16 @@ static int mxf_read_seek(AVFormatContext *s, int 
stream_index, int64_t sample_ti
 sample_time = FFMAX(sample_time, 0);

 if (t->fake_index) {
+/* The first frames may not be keyframes in presentation order, so
+ * we have to advance the target to be able to find the first
+ * keyframe backwards... */
+if (!(flags & AVSEEK_FLAG_ANY) &&
+(flags & AVSEEK_FLAG_BACKWARD) &&
+t->ptses[0] != AV_NOPTS_VALUE &&


Can the size of t->ptses ever be zero here?


No, "paranoid check" in mxf_compute_ptses_fake_index should ensure that.





+sample_time < t->ptses[0] &&
+(t->fake_index[t->ptses[0]].flags & AVINDEX_KEYFRAME))


Do t->ptses always point inside t->fake_index?


Yes, if it is not AV_NOPTS_VALUE, that is made sure when setting the 
ptses in mxf_compute_fake_index.





+sample_time = t->ptses[0];
+


Should be OK otherwise, since it only affects seeking and fixes a
regression.


Ok, applied, thanks.


Ideally we should be doing something better for seeking, I
think..


Well, yes...

Regards,
Marton
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Re: [FFmpeg-devel] [PATCH] lavf/mxfdec: fix seeking before the first keyframe

[Tomas Härdin]

On Sat, 2015-11-28 at 02:56 +0100, Marton Balint wrote:
> Regression since 53f2ef2c4afb1d49a679dea9163cb0e4671f3117.
> Fixes ticket #5017.
> 
> Signed-off-by: Marton Balint 
> ---
>  libavformat/mxfdec.c | 10 ++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
> index 429f46a..926d2a3 100644
> --- a/libavformat/mxfdec.c
> +++ b/libavformat/mxfdec.c
> @@ -3181,6 +3181,16 @@ static int mxf_read_seek(AVFormatContext *s, int 
> stream_index, int64_t sample_ti
>  sample_time = FFMAX(sample_time, 0);
>  
>  if (t->fake_index) {
> +/* The first frames may not be keyframes in presentation order, 
> so
> + * we have to advance the target to be able to find the first
> + * keyframe backwards... */
> +if (!(flags & AVSEEK_FLAG_ANY) &&
> +(flags & AVSEEK_FLAG_BACKWARD) &&
> +t->ptses[0] != AV_NOPTS_VALUE &&

Can the size of t->ptses ever be zero here?


> +sample_time < t->ptses[0] &&
> +(t->fake_index[t->ptses[0]].flags & AVINDEX_KEYFRAME))

Do t->ptses always point inside t->fake_index?

> +sample_time = t->ptses[0];
> +

Should be OK otherwise, since it only affects seeking and fixes a
regression. Ideally we should be doing something better for seeking, I
think..

/Tomas


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[FFmpeg-devel] [PATCH] lavf/mxfdec: fix seeking before the first keyframe

[Marton Balint]

Regression since 53f2ef2c4afb1d49a679dea9163cb0e4671f3117.
Fixes ticket #5017.

Signed-off-by: Marton Balint 
---
 libavformat/mxfdec.c | 10 ++
 1 file changed, 10 insertions(+)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 429f46a..926d2a3 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -3181,6 +3181,16 @@ static int mxf_read_seek(AVFormatContext *s, int 
stream_index, int64_t sample_ti
 sample_time = FFMAX(sample_time, 0);
 
 if (t->fake_index) {
+/* The first frames may not be keyframes in presentation order, so
+ * we have to advance the target to be able to find the first
+ * keyframe backwards... */
+if (!(flags & AVSEEK_FLAG_ANY) &&
+(flags & AVSEEK_FLAG_BACKWARD) &&
+t->ptses[0] != AV_NOPTS_VALUE &&
+sample_time < t->ptses[0] &&
+(t->fake_index[t->ptses[0]].flags & AVINDEX_KEYFRAME))
+sample_time = t->ptses[0];
+
 /* behave as if we have a proper index */
 if ((sample_time = ff_index_search_timestamp(t->fake_index, 
t->nb_ptses, sample_time, flags)) < 0)
 return sample_time;
-- 
2.6.2

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