Em 28-05-2011 09:44, Mauro Carvalho Chehab escreveu: >> Anyways I think we're are currently >> doing this the wrong way up. We should first discuss what such an API >> should look like and then implement it. Hopefully we can re-use a lot >> of the existing code when we do this, but I think it is better >> to first design the API and then write code to the API, the current >> API at least to me feels somewhat like an API written around existing >> code rather then the other way around. > > No, was just the opposite: the API were designed to fulfil the needs by > the alsa streaming methods implemented by Devin at tvtime: > > int alsa_thread_startup(const char *pdevice, const char *cdevice); > > The two arguments are the alsa playback device and the alsa capture device. > > the API were designed around that, to do something like: > > struct some_opaque_struct *opaque = discover_media_devices(); > alsa_playback = alsa_playback(opaque); > alsa_capture = alsa_capture(opaque); > alsa_thread_startup(alsa_playback, alsa_capture); > free_media_devices(opaque); > > PS.: I'm not using the real names/arguments at the above, to keep the example > simpler and clearer. The actual code is not that different from the above: > > struct media_devices *md; > unsigned int size = 0; > char *alsa_cap, *alsa_out, *p; > char *video_dev = "/dev/video0"; > > md = discover_media_devices(&size); > p = strrchr(video_dev, '/'); > alsa_cap = get_first_alsa_cap_device(md, size, p + 1); > alsa_out = get_first_no_video_out_device(md, size); > if (alsa_cap && alsa_out) > alsa_handler(alsa_out, alsa_cap); > free_media_devices(md, size); > ... > fd = open(video_dev, "rw"); I decided to re-organize the way the API will handle the devices, in order to make clearer that the internal struct should be opaque to the applications using the library [1]. [1] http://git.linuxtv.org/v4l-utils.git?a=commitdiff;h=435f4ba896f76d92a800a2089e06618d8c3d93f0 Now, the functions will just return a void pointer that is used as a parameter for the other functions. So, the typical usecase is, currently: void *md; char *alsa_playback, *alsa_capture, *p; md = discover_media_devices(); if (!md) return; alsa_capture = get_first_alsa_cap_device(md, video_dev); alsa_playback = get_first_no_video_out_device(md); if (alsa_capture && alsa_playback) alsa_handler(alsa_playback, alsa_capture); free_media_devices(md); I'll be working on improving the API, in order to read the uevent information from the media nodes (were device major/minor info are stored) and to associate a device with its file descriptor. Cheers, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
