Hans Verkuil wrote:
> On Wednesday 04 October 2006 23:10, Duncan Webb wrote:
>> Hans Verkuil wrote:
>>> On Wednesday 04 October 2006 22:39, Duncan Webb wrote:
>>>> Is there a mapping table that tells what the new V4L2 call is for
>>>> an old IVTV ioctl call?
>>> The ChangeLog file has this mapping in the 0.8 entry at the top.
>> Thanks for this
>>
>>>> I'm looking for the equivalent call for IVTV_IOC_G_DRIVER_INFO is.
>>> Use VIDIOC_QUERYCAP instead.
>> Doesn't tell me it the card can do mpeg decoding (has a
>> /dev/video16), where are IVTV_IOC_G_DRIVER_INFO did in a round about
>> way.
> 
> If the driver name returned by VIDIOC_QUERYCAP is 'ivtv', and if 
> V4L2_CAP_VIDEO_OUTPUT is set in the capabilities field, then the driver 
> can do mpeg decoding.

Thanks, I will check this out

> Using VIDIOC_ENUM_FMT and checking for the MPEG 
> pixelformat would be much more generic, but I discovered that ivtv 
> doesn't support this ioctl at the moment.
> 
>> Is there a way to start and stop mpeg stream. When the mpeg stream is
>> opened then we get a GOP, so what would be nice is to be able to stop
>> the stream at the end of a group of pictures and finish reading the
>> data (with out having to parse a buffer). Or even better open the
>> stream in a paused mode and then send a start to start the stream
>> running. (A bit like using threads)
> 
> If you call IVTV_IOC_S_GOP_END with arg 1, then the card won't stop 
> capturing until the end of a GOP is reached.

Oh great, just what I want.

>> Last question is there much overhead on opening a video device in
>> order to determine if the device is busy of is there a better way.
>> The idea is if something is using the tuner like watching TV or
>> listening to the radio just before a recording is about to start I
>> want to stop this action and start recording.
> 
> That overhead is quite small AFAIK.

I found that I can open the video device when it is already in use
without any errors, it doesn't return EBUSY until data has been read.
Might be a bit cleaner if there is an ioctl for this.

Thanks, again.

> Regards,
> 
>       Hans
> 
>> TIA
>> Duncan
>>
>>
>>
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> 
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