Re: [Opensvcdecoder-support] What is a ghost picture?

[Siyuan X. <xia...@gm...>]

Dear Médéric,

Thank you very much! It works!
I download the latest version and use PC.c instead of H264_plg.c, I do not
know how to use H264_plg.c.  Is this used for TCPMP?
Anyway, every layer can be decoded. :)

Regards,
Siyuan Xiang
---



On Thu, Mar 17, 2011 at 02:19, Médéric Blestel <
Med...@in...> wrote:

>  Dear Siyuan,
>
> It seems that the stream is correctly decoded with the last version of the
> decoder.
> Can you confirm it?
>
> I join you the last version of the h264_plg.c file.
>
> Kind regards,
> Médéric
>
>
> Le 14/03/2011 20:51, Siyuan Xiang a écrit :
>
> I see. Thank you Mickael and Mederic.
>
>  I get an access violation when decoding a bitstream, which has 6 layers.
> The configuration is  320x180 (2 quality layers), 640x360 (2 quality
> layers), 1280x720 (2 quality layers). Each layer has the same frame rate
> 24.
>
>  The lower resolutions can be decoded without problem. But when I set the
> DqID to 32 or 33, decoding the 1280x720 resolution, I will get access
> violation at mb4x4_mode [mode](ptr_img, PicWidthInPix, residu -> AvailMask,
> locx, locy); in file 264_baseline_decoder\lib_baseline\decode_MB_I.c.
>
>  It seems that mode is larger than the array size.
>
>  I divide the source video into segment of 17 frames and encode them
> separately, then concatenate them together. The bitstream has 17x5 = 85
> frames.
>
>
>
>
> Regards,
> Siyuan
> ---
>
>
>
> On Mon, Mar 14, 2011 at 02:04, Médéric Blestel <
> Med...@in...> wrote:
>
>> Dear Siyuan,
>>
>> To clarify the ghost picture discussion.
>> *ImageToDisplay is equals to 2 when a temporal layer has been detected in
>> another layer.
>>
>> This mechanism helps to keep the frame rate between all layers.
>> In fact, when temporal scalability is present, each layer has got
>> different number of frames.
>>
>> For instance, with a 2 temporal layer (and 1 enhancement layer):
>>    - Base layer: 150 frames at 15 fps
>>    - Top layer: 300 frames at 30 fps.
>>
>> Each layer has to be decoded at different frame rate, between the stream
>> duration is the same (10 s).
>> Without this mechanism, the base layer would be decoded at 30 fps instead
>> of 15 fps. So to keep the same video duration,
>> *ImageToDisplay is set to 2, and a frame is displayed, and will be
>> displayed again with *ImageToDisplay = 1.
>>
>> Kind regards,
>> Médéric
>>
>>
>> Le 14/03/2011 09:26, Mickaël Raulet a écrit :
>>
>>  With a temporal layer with a lower frame rate, we are inserting ghost
>>> pictures to give the same framerate of the enhancement layers.
>>> Mickaël
>>>
>>> Le 14 mars 2011 à 09:23, Siyuan Xiang a écrit :
>>>
>>>  Hi, all,
>>>>
>>>> I downloaded the latest source from svn, now all the frames can be
>>>> flushed out.
>>>> I tried a 17-picture bitstream, but found 18 pictures are displayed. The
>>>> second displayed picture is a ghost picture (I checked *ImageToDisplay which
>>>> is equal to 2).
>>>> What is a ghost picture? Can I just ignore the ghost picture?
>>>>
>>>> By the way, I found the decoding is faster than before :)
>>>>
>>>> Regards,
>>>> Siyuan
>>>> ---
>>>>
>>>>
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