[FFmpeg-devel] camera files (no name)

[nicolas martin]

Le 09-02-06 ? 18:51, Vitor Sessak a ?crit :

> nicolas martin wrote:
>>
>> Le 09-02-06 ? 16:52, Michael Niedermayer a ?crit :
>>
>>> On Fri, Feb 06, 2009 at 04:26:02PM -0500, nicolas martin wrote:
>>>>
>>>> Le 09-02-06 ? 14:06, Michael Niedermayer a ?crit :
>>>>
>>>>> On Fri, Feb 06, 2009 at 01:43:27PM -0500, nicolas martin wrote:
>>>>>>
>>>>>> Le 09-02-06 ? 12:20, Michael Niedermayer a ?crit :
>>>>>>
>>>>>>> On Fri, Feb 06, 2009 at 08:14:30AM -0500, nicolas martin wrote:
>>>>>>>>
>>>>>>>>> On Wed, Feb 04, 2009 at 01:23:16PM -0500, nicolas martin  
>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> On Tue, Feb 03, 2009 at 04:27:51PM -0500, nicolas martin  
>>>>>>>>>>> wrote:
>>>>>>>>>>>> Attached is a patch to support the nc4600 camera files.
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks in advance for reviewing and replying.
>>>>>>>>>>>
>>>>>>>>>>> Changelog and docs update is missing.
>>>>>>>>>>
>>>>>>>>>> Doc update and changelog since when ?
>>>>>>>>>
>>>>>>>>> If you add a new demuxer, you should add an entry for it to  
>>>>>>>>> the
>>>>>>>>> changelog and the format support list in doc/general.texi.
>>>>>>>>>
>>>>>>>>
>>>>>>>> In reply to what Peter Ross wrote, I can't find its mail though
>>>>>>>>
>>>>>>>>>>> + if (size <= 0) {
>>>>>>>>>>> + av_log(s, AV_LOG_DEBUG, "Wrong size : %d\n", size);
>>>>>>>>>> While size may be zero, it will never be less then zero,  
>>>>>>>>>> thus the
>>>>>>>>>> debug
>>>>>>>>>> statement is pointless.
>>>>>>>> The size can't be less than zero, I changed it.
>>>>>>>> However if the size is zero, then we have a problem, so the  
>>>>>>>> debug
>>>>>>>> statement
>>>>>>>> is meaningful.
>>>>>>>
>>>>>>> [...]
>>>>>>>> +static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
>>>>>>>> +{
>>>>>>>> +    int size;
>>>>>>>> +
>>>>>>>> +    uint32_t state=-1;
>>>>>>>> +    while(!url_feof(s->pb) && state != NC_VIDEO_FLAG)
>>>>>>>> +        state = (state<<8) + get_byte(s->pb);
>>>>>>>> +
>>>>>>>> +    get_byte(s->pb);
>>>>>>>> +    size = get_le16(s->pb);
>>>>>>>> +    url_fskip(s->pb, 9);
>>>>>>>> +
>>>>>>>
>>>>>>>> +    if (size == 0) {
>>>>>>>> +        av_log(s, AV_LOG_DEBUG, "Wrong size : %d\n", size);
>>>>>>>> +        return AVERROR_INVALIDDATA;
>>>>>>>> +    }
>>>>>>>
>>>>>>> what is the problem with not returning an error in this case?
>>>>>>
>>>>>> Well I think that the camera is not supposed to send packet with
>>>>>> size 0.
>>>>>> If
>>>>>> it happens, it probably means the data got corrupted, or an error
>>>>>> occured.
>>>>>> In any case, I don't think you can do anything besides  
>>>>>> returning an
>>>>>> error
>>>>>> ... maybe try to skip data until the next header ??
>>>>>> As I don't think it is supposed to happen, I choose to treat it  
>>>>>> like
>>>>>> this.
>>>>>> What do you think ??
>>>>>
>>>>> id print a warning and continue, the code should be able to find  
>>>>> and
>>>>> continue
>>>>> at the next valid frame
>>>>
>>>> Ok so I changed it so that while (size==0) it loops until it  
>>>> finds a
>>>> valid
>>>> size.
>>>> Though i think it should never happen, if it happens, better pray
>>>> that it's
>>>> a corrupted data,
>>>> my guess is that it will loop forever ...
>>>> Should I add a count to break if it repeateadly gives a null size ?
>>>> or is
>>>> the solution I brought enough ?
>>>
>>> it should fail at EOF to prevent an infinite loop
>>> and it might make sense to retun EAGAIN instead of looping, this  
>>> also
>>> might be simpler
>>
>> What about something like that ?
>
> I was going to apply, but it failed to decode the first sample you  
> sent
> (ftp://upload.mplayerhq.hu/incoming/nc_camera/nc_sample.avi), giving
> repeatedly the message:
>
>  [nc @ 0x88e3b60]Next paquet size is zero

Is there a way I can get this sample back on the ftp ?
I can't seem to find it and all the samples I have decode well !
Thanks!

>
>
> The second sample plays fine, but I'm not sure if in the correct  
> speed.
> Also, since you'll have to do another version anyway, one nit:
>
>> +
>> +    if (size == 0) {
>> +        av_log(s, AV_LOG_DEBUG, "Next paquet size is zero\n");
>
> Next _packet_...

Changed.

>
>
> -Vitor
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