[FFmpeg-devel] camera files (no name)

[Michael Niedermayer]

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

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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