[FFmpeg-devel] [PATCH 5/8] lavd: add device capabilities API

Don Moir donmoir at comcast.net
Thu Apr 10 23:57:26 CEST 2014


----- Original Message ----- 
From: "Lukasz Marek" <lukasz.m.luki2 at gmail.com>
To: <ffmpeg-devel at ffmpeg.org>
Sent: Thursday, April 10, 2014 4:34 PM
Subject: Re: [FFmpeg-devel] [PATCH 5/8] lavd: add device capabilities API


> On 10.04.2014 02:32, Don Moir wrote:
>> Did you mean: by how or by now :)
>>
>> +typedef struct AVDeviceCapabilitiesQuery {
>> +    const AVClass *class;
>> +    AVFormatContext *device_context;
>> +    enum AVCodecID codec;
>> +    enum AVSampleFormat sample_format;
>> +    enum AVPixelFormat pixel_format;
>> +    int sample_rate;
>> +    int channels;
>> +    int64_t channel_layout;
>> +    int window_width;
>> +    int window_height;
>> +    int frame_width;
>> +    int frame_height;
>> +    AVRational fps;
>> +} AVDeviceCapabilitiesQuery;
>>
>> For a capture device and for each pixel format, width, and height, there
>> can be a range of FPS values, like a min of a 1 FPS to max 60 FPS. Just
>> varies for each device and format. So don't see how that fits into the
>> AVDeviceCapabilitiesQuery structure as it stands.
>
> You query this structure, not use to store all possible values. Read an example and doc, it is described.

Not following thread very close so forgive is this is out of place. Ok you get device list and then what? Query every possible 
value? Maybe somewhere else and not seeing it. How many queries would I have to do to get all possible formats, widths, heights and 
frames rates that a device might support? I don't know. 



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