On 1/10/2017 6:26 AM, wm4 wrote:
> On Tue, 10 Jan 2017 09:01:12 +0100
> Anton Khirnov <[email protected]> wrote:
> 
>> The current condition can trigger in cases where it shouldn't, with
>> unexpected results.
>> Make sure that:
>> - container cropping is really based on the original dimensions from the
>>   caller
>> - those dimenions are discarded on size change
>>
>> The code is still quite hacky and eventually should be deprecated and
>> removed, with the decision about which cropping is used delegated to the
>> caller.
>> ---
>>  libavcodec/h264_slice.c | 15 +++++++++++----
>>  libavcodec/h264dec.c    |  3 +++
>>  libavcodec/h264dec.h    |  5 +++++
>>  3 files changed, 19 insertions(+), 4 deletions(-)
>>
>> diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
>> index 1b35c2b..a54d381 100644
>> --- a/libavcodec/h264_slice.c
>> +++ b/libavcodec/h264_slice.c
>> @@ -378,6 +378,8 @@ int ff_h264_update_thread_context(AVCodecContext *dst,
>>      h->avctx->coded_width   = h1->avctx->coded_width;
>>      h->avctx->width         = h1->avctx->width;
>>      h->avctx->height        = h1->avctx->height;
>> +    h->width_from_caller    = h1->width_from_caller;
>> +    h->height_from_caller   = h1->height_from_caller;
>>      h->coded_picture_number = h1->coded_picture_number;
>>      h->first_field          = h1->first_field;
>>      h->picture_structure    = h1->picture_structure;
>> @@ -797,10 +799,15 @@ static int init_dimensions(H264Context *h)
>>      int height = h->height - (sps->crop_top   + sps->crop_bottom);
>>  
>>      /* handle container cropping */
>> -    if (FFALIGN(h->avctx->width,  16) == FFALIGN(width,  16) &&
>> -        FFALIGN(h->avctx->height, 16) == FFALIGN(height, 16)) {
>> -        width  = h->avctx->width;
>> -        height = h->avctx->height;
>> +    if (h->width_from_caller > 0 && h->height_from_caller > 0     &&
>> +        !sps->crop_top && !sps->crop_left                         &&
>> +        FFALIGN(h->width_from_caller,  16) == FFALIGN(width,  16) &&
>> +        FFALIGN(h->height_from_caller, 16) == FFALIGN(height, 16)) {
>> +        width  = h->width_from_caller;
>> +        height = h->height_from_caller;
>> +    } else {
>> +        h->width_from_caller  = 0;
>> +        h->height_from_caller = 0;
>>      }
>>  
>>      h->avctx->coded_width  = h->width;
>> diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
>> index e111d40..3209c1d 100644
>> --- a/libavcodec/h264dec.c
>> +++ b/libavcodec/h264dec.c
>> @@ -285,6 +285,9 @@ static int h264_init_context(AVCodecContext *avctx, 
>> H264Context *h)
>>  
>>      h->avctx                 = avctx;
>>  
>> +    h->width_from_caller     = avctx->width;
>> +    h->height_from_caller    = avctx->height;
>> +
>>      h->picture_structure     = PICT_FRAME;
>>      h->workaround_bugs       = avctx->workaround_bugs;
>>      h->flags                 = avctx->flags;
>> diff --git a/libavcodec/h264dec.h b/libavcodec/h264dec.h
>> index 5957e79..0a9896a 100644
>> --- a/libavcodec/h264dec.h
>> +++ b/libavcodec/h264dec.h
>> @@ -514,6 +514,11 @@ typedef struct H264Context {
>>       * the slice data */
>>      int field_started;
>>  
>> +    /* original AVCodecContext dimensions, used to handle container
>> +     * cropping */
>> +    int width_from_caller;
>> +    int height_from_caller;
>> +
>>      AVFrame *output_frame;
>>  
>>      int enable_er;
> 
> Is this kind of cropping even commonly used? Which containers?

Matroska.

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