[libav-devel] [PATCH v2] zerocodec: check if there is previous frame

2012-05-04 Thread Derek Buitenhuis 
From: Paul B Mahol one...@gmail.com

Signed-off-by: Paul B Mahol one...@gmail.com
---
 libavcodec/zerocodec.c |4 
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/zerocodec.c b/libavcodec/zerocodec.c
index 6c57e05..7a0ba34 100644
--- a/libavcodec/zerocodec.c
+++ b/libavcodec/zerocodec.c
@@ -65,6 +65,10 @@ static int zerocodec_decode_frame(AVCodecContext *avctx, 
void *data,
 pic-key_frame = 1;
 pic-pict_type = AV_PICTURE_TYPE_I;
 } else {
+if (!prev) {
+av_log(avctx, AV_LOG_ERROR, No previous frame!\n);
+return AVERROR_INVALIDDATA;
+}
 pic-key_frame = 0;
 pic-pict_type = AV_PICTURE_TYPE_P;
 }
-- 
1.7.10

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Re: [libav-devel] [PATCH v2] zerocodec: check if there is previous frame

2012-05-04 Thread Kostya Shishkov 
On Fri, May 04, 2012 at 12:32:43PM -0400, Derek Buitenhuis wrote:
 From: Paul B Mahol one...@gmail.com
 
 Signed-off-by: Paul B Mahol one...@gmail.com
 ---
  libavcodec/zerocodec.c |4 
  1 file changed, 4 insertions(+)
 
 diff --git a/libavcodec/zerocodec.c b/libavcodec/zerocodec.c
 index 6c57e05..7a0ba34 100644
 --- a/libavcodec/zerocodec.c
 +++ b/libavcodec/zerocodec.c
 @@ -65,6 +65,10 @@ static int zerocodec_decode_frame(AVCodecContext *avctx, 
 void *data,
  pic-key_frame = 1;
  pic-pict_type = AV_PICTURE_TYPE_I;
  } else {
 +if (!prev) {
 +av_log(avctx, AV_LOG_ERROR, No previous frame!\n);
 +return AVERROR_INVALIDDATA;
 +}
  pic-key_frame = 0;
  pic-pict_type = AV_PICTURE_TYPE_P;
  }
 -- 

OK
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Re: [libav-devel] [PATCH v2] zerocodec: check if there is previous frame

2012-05-04 Thread Diego Biurrun 
On Fri, May 04, 2012 at 12:32:43PM -0400, Derek Buitenhuis wrote:
 From: Paul B Mahol one...@gmail.com

.. if there is _a_ previous ..

 --- a/libavcodec/zerocodec.c
 +++ b/libavcodec/zerocodec.c
 @@ -65,6 +65,10 @@ static int zerocodec_decode_frame(AVCodecContext *avctx, 
 void *data,
  pic-key_frame = 1;
  pic-pict_type = AV_PICTURE_TYPE_I;
  } else {
 +if (!prev) {
 +av_log(avctx, AV_LOG_ERROR, No previous frame!\n);
 +return AVERROR_INVALIDDATA;

I admittedly don't know the surrounding code, but the error message does
not make much sense to me.  Why is the lack of a previous frame an error
condition?  And when does this happen except on the first frame?

Diego
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Re: [libav-devel] [PATCH v2] zerocodec: check if there is previous frame

2012-05-04 Thread Derek Buitenhuis 
On 04/05/2012 12:48 PM, Diego Biurrun wrote:
 I admittedly don't know the surrounding code, but the error message does
 not make much sense to me.  Why is the lack of a previous frame an error
 condition?  And when does this happen except on the first frame?

ZeroCodec relies on the keyframe flag being set in the container, and prev
is the previously decoded frame. So, e.g., if you have a file with incorrect
or missing keyframe flags, this can happen.

- Derek
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Re: [libav-devel] [PATCH v2] zerocodec: check if there is previous frame

2012-05-04 Thread Mashiat Sarker Shakkhar 

On 5/4/2012 10:54 PM, Derek Buitenhuis wrote:

On 04/05/2012 12:48 PM, Diego Biurrun wrote:

I admittedly don't know the surrounding code, but the error message does
not make much sense to me.  Why is the lack of a previous frame an error
condition?  And when does this happen except on the first frame?


ZeroCodec relies on the keyframe flag being set in the container, and prev
is the previously decoded frame. So, e.g., if you have a file with incorrect
or missing keyframe flags, this can happen.

[...]

I am in favor of using a more comprehensive error message here. Just 
saying ...


Shakkhar
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