[FFmpeg-devel] camera files (no name)

[nicolas martin]

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 ??

>
>
>
>> +
>> +    if (av_get_packet(s->pb, pkt, size) != size)
>> +        return AVERROR(EIO);
>
> if the return is >0 but != size then this leaks a packet

Fixed.

>
>
>
> [...]
> -- 
> Michael     GnuPG fingerprint:  
> 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Opposition brings concord. Out of discord comes the fairest harmony.
> -- Heraclitus
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