[FFmpeg-devel] [PATCH] H.264 fix interlaced flag

[Ivan Schreter]

Hi,

Michael Niedermayer wrote:
> On Tue, Mar 03, 2009 at 07:49:53PM +0100, Ivan Schreter wrote:
>   
>> [...]
>> Index: libavcodec/h264.c
>> ===================================================================
>> --- libavcodec/h264.c	(revision 17723)
>> +++ libavcodec/h264.c	(working copy)
>> @@ -6805,7 +6805,7 @@
>>          for (i = 0 ; i < num_clock_ts ; i++){
>>              if(get_bits(&s->gb, 1)){                  /* clock_timestamp_flag */
>>                  unsigned int full_timestamp_flag;
>> -                skip_bits(&s->gb, 2);                 /* ct_type */
>> +                h->sei_ct_type[i] = get_bits(&s->gb, 2);
>>     
>
> h->sei_ct_type |= 1<<get_bits(&s->gb, 2);
> stores things in a, for us easier to use form
>
>   
Hm, I could come to this idea to use bitset myself :-)

> [...]
>
>   
>> @@ -7767,20 +7784,22 @@
>>                  switch (h->sei_pic_struct)
>>                  {
>>                  case SEI_PIC_STRUCT_FRAME:
>> -                    cur->interlaced_frame = 0;
>> +                    cur->interlaced_frame = h264_is_interlaced(h);
>>                      break;
>>                  case SEI_PIC_STRUCT_TOP_FIELD:
>>                  case SEI_PIC_STRUCT_BOTTOM_FIELD:
>> +                    cur->interlaced_frame = 1;
>> +                    break;
>>                  case SEI_PIC_STRUCT_TOP_BOTTOM:
>>                  case SEI_PIC_STRUCT_BOTTOM_TOP:
>> -                    cur->interlaced_frame = 1;
>> +                    cur->interlaced_frame = h264_is_interlaced(h);
>>                      break;
>>                  case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
>>                  case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
>>                      // Signal the possibility of telecined film externally (pic_struct 5,6)
>>                      // From these hints, let the applications decide if they apply deinterlacing.
>>                      cur->repeat_pict = 1;
>> -                    cur->interlaced_frame = FIELD_OR_MBAFF_PICTURE;
>> +                    cur->interlaced_frame = h264_is_interlaced(h);
>>                      break;
>>                  case SEI_PIC_STRUCT_FRAME_DOUBLING:
>>                      // Force progressive here, as doubling interlaced frame is a bad idea.
>>     
>
> this is incorrect
> ct_type should always be used if available, otherwise
> FIELD_OR_MBAFF_PICTURE should be.
> that at least is how i understand the spec, if this fails for some
> case iam interrested in the file
>   
Updated patch attached.

BTW, I left frame doubling and tripling set interlaced to false. To be 
completely consistent, possibly this should be done via ct_type as well 
(but doubling and tripling will surely look bad interlaced...). What do 
you think?

Regards,

Ivan

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