[FFmpeg-devel] [PATCH] H.264fixinterlacedflag:bringback pic_struct
Haruhiko Yamagata
h.yamagata
Tue Jun 2 13:59:10 CEST 2009
>On Sun, May 31, 2009 at 05:42:37PM +0900, Haruhiko Yamagata wrote:
>>> On Fri, May 29, 2009 at 07:18:22PM +0900, Haruhiko Yamagata wrote:
>>>>> On Thu, May 28, 2009 at 11:23:17PM +0900, Haruhiko Yamagata wrote:
>>>>>>> On Thu, May 28, 2009 at 10:59:09PM +0900, Haruhiko Yamagata wrote:
>>>>>>>>> On Thu, May 28, 2009 at 09:24:59PM +0900, Haruhiko Yamagata wrote:
>>>>>>>>>> On Tue, Mar 03, 2009, Michael Niedermayer wrote:
>>>>>>>>>>> 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
>>>>>>>>>>
>>>>>>>>>> Excuse me for late response, I found a file which fails.
>>>>>>>>>> http://x264.nl/h.264.samples/premiere-paff.ts
>>>>>>>>>>
>>>>>>>>>> Please note that ct_type is optional in the picture timing SEI.
>>>>>>>>>>
>>>>>>>>>>> if(get_bits(&s->gb, 1)){ /*
>>>>>>>>>>> clock_timestamp_flag */
>>>>>>>>>>> unsigned int full_timestamp_flag;
>>>>>>>>>>> h->sei_ct_type |= 1<<get_bits(&s->gb, 2);
>>>>>>>>>>
>>>>>>>>>> That file does not have ct_type at all, but has correct pic_struct.
>>>>>>>>>> pic_struct is basically correct, only a few streams are badly
>>>>>>>>>> encoded.
>>>>>>>>>> The attached patch fixes this issue and still honor ct_type if
>>>>>>>>>> available.
>>>>>>>>>>
>>>>>>>>>> Best regards,
>>>>>>>>>> Haruhiko Yamagata
>>>>>>>>>
>>>>>>>>>> h264.c | 19 +++++++++++++------
>>>>>>>>>> 1 file changed, 13 insertions(+), 6 deletions(-)
>>>>>>>>>> 832b6de132e2ccb691445f47a3ee3b56d0b1e65d
>>>>>>>>>> check_presence_of_cy_type.patch
>>>>>>>>>> Index: libavcodec/h264.c
>>>>>>>>>> ===================================================================
>>>>>>>>>> --- libavcodec/h264.c (revision 18971)
>>>>>>>>>> +++ libavcodec/h264.c (working copy)
>>>>>>>>>> @@ -6866,7 +6866,7 @@
>>>>>>>>>> for (i = 0 ; i < num_clock_ts ; i++){
>>>>>>>>>> if(get_bits(&s->gb, 1)){ /*
>>>>>>>>>> clock_timestamp_flag */
>>>>>>>>>> unsigned int full_timestamp_flag;
>>>>>>>>>> - h->sei_ct_type |= 1<<get_bits(&s->gb, 2);
>>>>>>>>>> + h->sei_ct_type |= 1<<(get_bits(&s->gb, 2)+1);
>>>>>>>>>> skip_bits(&s->gb, 1); /*
>>>>>>>>>> nuit_field_based_flag */
>>>>>>>>>> skip_bits(&s->gb, 5); /*
>>>>>>>>>> counting_type */
>>>>>>>>>
>>>>>>>>> why?
>>>>>>>>
>>>>>>>> So that h->sei_ct_type will be none zero if ct_type exists, even if
>>>>>>>> ct_type is zero.
>>>>>>>> In other words, h->sei_ct_type shall be zero if ct_type does not
>>>>>>>> exit.
>>>>>>>
>>>>>>> so 1<<0 is 0 for you?
>>>>>>
>>>>>> My mistake.
>>>>>> A new patch attached.
>>>>> [...]
>>>>>> @@ -7819,6 +7823,9 @@
>>>>>> cur->interlaced_frame = FIELD_OR_MBAFF_PICTURE;
>>>>>> }
>>>>>> + if (h->sei_ct_type)
>>>>>> + cur->interlaced_frame = (h->sei_ct_type & (1<<1)) !=
>>>>>> 0;
>>>>>
>>>>> this overrides the value set from SEI_PIC_STRUCT_FRAME_TRIPLING:
>>>>
>>>> Yes, I moved the two lines into if(h->sps.pic_struct_present_flag) block
>>>> and
>>>> added check.
>>>>
>>>> Best regards,
>>>> Haruhiko Yamagata
>>>
>>>> h264.c | 17 ++++++++++++-----
>>>> 1 file changed, 12 insertions(+), 5 deletions(-)
>>>> 3d86c0ddddd340d6af20ef493f043900ed02cc43
>>>> check_presence_of_ct_type_3.patch
>>>> Index: libavcodec/h264.c
>>>> ===================================================================
>>>> --- libavcodec/h264.c (revision 18980)
>>>> +++ libavcodec/h264.c (working copy)
>>>> @@ -7790,14 +7790,18 @@
>>>> /* Signal interlacing information externally. */
>>>> /* Prioritize picture timing SEI information over used
>>>> decoding process if it exists. */
>>>> - if (h->sei_ct_type)
>>>> - cur->interlaced_frame = (h->sei_ct_type & (1<<1)) != 0;
>>>> - else
>>>> - cur->interlaced_frame = FIELD_OR_MBAFF_PICTURE;
>>>> -
>>>> if(h->sps.pic_struct_present_flag){
>>>> switch (h->sei_pic_struct)
>>>> {
>>>> + case SEI_PIC_STRUCT_FRAME:
>>>> + cur->interlaced_frame = 0;
>>>> + break;
>>>> + case SEI_PIC_STRUCT_TOP_FIELD:
>>>> + case SEI_PIC_STRUCT_BOTTOM_FIELD:
>>>> + case SEI_PIC_STRUCT_TOP_BOTTOM:
>>>> + case SEI_PIC_STRUCT_BOTTOM_TOP:
>>>> + cur->interlaced_frame = 1;
>>>> + 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)
>>>> @@ -7814,6 +7818,9 @@
>>>> cur->repeat_pict = 4;
>>>> break;
>>>> }
>>>> +
>>>> + if (h->sei_ct_type && h->sei_pic_struct <=
>>>> SEI_PIC_STRUCT_BOTTOM_TOP)
>>>> + cur->interlaced_frame = (h->sei_ct_type & (1<<1)) !=
>>>> 0;
>>>
>>> i think that leaves at least one case where interlaced_frame frame is not
>>> initialized
>>>
>>>
>>>> }else{
>>>> /* Derive interlacing flag from used decoding process.
>>>> */
>>>> cur->interlaced_frame = FIELD_OR_MBAFF_PICTURE;
>>
>> In this case, neither pic_struct nor ct_type is available.
>> This is the best information that we can have here.
>> Both pic_struct and ct_type are under pic_struct_present_flag.
>
>ct_type is under clock_timestamp_flag, pic_struct is not
>also ct_type can be set to "unknown" the code should fallback to someting
>else in that case
The spec says
> If CpbDpbDelaysPresentFlag is equal to 1 or pic_struct_present_flag is equal to 1,
> one picture timing SEI message shall be present in every access unit of the coded
> video sequence.
So if pic_struct_present_flag is equal to 1, decode_picture_timing shall be called
and h->sei_ct_type shall be flagged unknown (0) or set correct value.
In my patch,
> + if (h->sei_ct_type && h->sei_pic_struct <=
Presence of ct_type is checked here. This is only referenced
if pic_struct_present_flag is equal to 1.
Best regards,
Haruhiko Yamagata
More information about the ffmpeg-devel
mailing list