You Sir, are awesome.
I think this seems to be exactly what I was looking for...
Can I ask for JS code that does the periodic polling from the client
please and possibly the appropriate bits of the template?
Many thanks!
W
On 3 November 2010 11:10, Tom Evans <tevans...@googlemail.com> wrote:
> On Tue, Nov 2, 2010 at 5:12 PM, wawa wawawa <wazawaz...@gmail.com> wrote:
>> Hi All,
>>
>> So, I've got my django app, rabbitmq and celery working and processing
>> my uploaded files. Next step is to get the client to display status
>> results provided by JSON, ultimately refreshing to a results page when
>> complete.
>>
>> I'm a little new to JSON / AJAX (AJAJ!) and I'm struggling a little
>> with the templates and views part.
>>
>> Are there any easy examples out there?
>>
>> I can't seem to find any!
>>
>> Many thanks in advance for any suggestions.
>>
>> Cheers
>>
>> W
>>
>
> Sure. I have a TV recording system built using Django (the UI is web
> based), which records TV shows to disk in MPEG2 format. I then use the
> whole celery stack to convert those video files into something that I
> can then load up onto my ipad/iphone.
>
> The transcoding is initiated by a user clicking an icon on the episode
> page, which triggers an AJAX call, which eventually calls this
> function:
>
> def setup_transcode_episode(episode):
> data = { 'valid': False, }
> if episode.media:
> file = unicode(episode.media)
> rv = transcode_episode_for_ipad.delay(file=file, episode_id=episode.id)
> tm, created = TaskMeta.objects.get_or_create(task_id=rv.task_id)
> episode.ipad_media = tm
> episode.save()
> data['task_id'] = rv.task_id
> data['valid'] = True
> return data
>
> The data dictionary is returned back to the client, which now
> periodically polls a view for status, using the task_id.
>
> The task that is invoked, transcode_episode_for_ipad, looks like this:
>
> @task
> def transcode_episode_for_ipad(file, episode_id, **kwargs):
> args = make_ipad_encoder_args(file=file)
> out = args[-1]
> ffmpeg = FFmpegProgressMonitor(file=file, task_id=kwargs['task_id'],
> args=args)
> rv = ffmpeg.process()
> episode = TVEpisode.objects.get(id=episode_id)
> dir, fn = out.rsplit('/', 1)
> imedia = MplayerFileMedia.objects.create(directory=dir, file=fn)
> episode.ipad_media = imedia
> episode.save()
> return rv
>
> This is pretty straight-forward, I simply produce the arguments for
> ffmpeg, and then process it, monitoring the output of the ffmpeg to
> give me hints about how long through the transcoding process we are,
> which I then store in memcache, to avoid requiring a database hit to
> find out the status of the task.
> This is easier than it sounds, every <n> frames, ffmpeg prints out a
> line indicating how far through the file it is. Just monitor the
> output and update the cache as appropriate.
>
> The way my models are set up, TVEpisode.ipad_media is a generic
> foreign key, so while transcoding is taking place it points at the
> TaskMeta object, which contains the task id. This allows us to know
> that the task is underway in the background, even if we didn't
> initiate it ourselfs, and use that information to poll for status etc
> as appropriate.
>
> Cheers
>
> Tom
>
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