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

[Don Moir]

--- a/libavdevice/avdevice.h
+++ b/libavdevice/avdevice.h
@@ -43,6 +43,9 @@
  * @}
  */
 
+#include "libavutil/log.h"
+#include "libavutil/opt.h"
+#include "libavutil/dict.h"
 #include "libavformat/avformat.h"
 
 /**
@@ -228,6 +231,131 @@ int avdevice_dev_to_app_control_message(struct AVFormatContext *s,
                                         void *data, size_t data_size);
 
 /**
+ * Following API allows user to probe device capabilities (supported codecs,
+ * pixel formats, sample formats, resolutions, channel counts, etc).
+ * It is build on top op AVOption API.
+ * Queried capabilities allows to set up converters of video or audio
+ * parameters that fit to the device.
+ *
+ * List of capablities that can be queried:
+ *  - Capabilities valid for both audio and video devices:
+ *    - codec:          supported audio/video codecs.
+ *                      type: AV_OPT_TYPE_INT (AVCodecID value)
+ *  - Capabilities valid for audio devices:
+ *    - sample_format:  supported sample formats.
+ *                      type: AV_OPT_TYPE_INT (AVSampleFormat value)
+ *    - sample_rate:    supported sample rates.
+ *                      type: AV_OPT_TYPE_INT
+ *    - channels:       supported number of channels.
+ *                      type: AV_OPT_TYPE_INT
+ *    - channel_layout: supported channel layouts.
+ *                      type: AV_OPT_TYPE_INT64

Following should be: *  - Capabilities valid for video devices:
+ *  - Capabilities valid for audio devices:

+ *    - pixel_format:   supported pixel formats.
+ *                      type: AV_OPT_TYPE_INT (AVPixelFormat value)
+ *    - window_size:    supported window sizes (describes size of the window size presented to the user).
+ *                      type: AV_OPT_TYPE_IMAGE_SIZE
+ *    - frame_size:     supported frame sizes (describes size of provided video frames).
+ *                      type: AV_OPT_TYPE_IMAGE_SIZE
+ *    - fps:            supported fps values
+ *                      type: AV_OPT_TYPE_RATIONAL

FPS can be a range for capture devices

----- Original Message ----- 
From: "Lukasz Marek" <lukasz.m.luki2 at gmail.com>
To: <ffmpeg-devel at ffmpeg.org>
Sent: Wednesday, April 09, 2014 4:33 PM
Subject: Re: [FFmpeg-devel] [PATCH 5/8] lavd: add device capabilities API


> On 05.04.2014 23:14, Michael Niedermayer wrote:
>> On Sat, Apr 05, 2014 at 10:58:37PM +0200, wm4 wrote:
>>> On Sat, 5 Apr 2014 22:47:37 +0200
>>> Michael Niedermayer <michaelni at gmx.at> wrote:
>>>
>>>> On Sat, Apr 05, 2014 at 10:17:33PM +0200, Lukasz Marek wrote:
>>>
>>>>> I still think this there should be separate struct to store them in
>>>>> both cases.
>>>>> It can be moved to AVFormatContext to simplify API, but avformat
>>>>> need to know size of the structure. It is avdevice specific so I
>>>>> don't know if moving it to avformat is good idea. I can add alloc
>>>>> function in libavdevice, but it will create dependency.
>>>>> I don't know if it all is worth removing 2 simple API calls.
>>>>
>>>> well, if people are happy with how it is with teh 2 calls, i dont mind
>>>
>>> What people? Is anyone else working on / using the stuff discussed here?
>>
>> The API discussed here allows to get the capabilities of devices
>> but they are technically muxers and demuxers, so maybe this API
>> would at some point in the future also be used for gathering the
>> capabilities of muxers and demuxers
> 
> 
> I attached a bit updated version.
> I separated sample format and pixel format (it had common field format). 
> It could be a problem in case some device can handle both.
> 
> I'm almost done with implementation of the API for pulseaudio and opengl 
> so it is quite well tested from developer point of view.
> 
> If there are no other remarks than you can merge this one.
> 
>


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