As mentioned in my previous blog entry I am working on multistream handling in Transmageddon. Not been a lot of changes, but I have been able to put in a little time here and there. The changes needed to accommodate this have also cleaned up the codebase quite a bit in my opinion, moving from a forest of variables to a list of python dictionaries. This change makes keeping track of whats happening in the codepath a lot easier as I can now just print the dictionary from the list to see what all relevant values are at a given point. Anyway a little screenshot below to show where I am at:
Still quite a bit of work to do to clean up the codebase and decide how certain things are to be handled (or not handled), but it is getting there. Screenshot above actually demonstrates one thing I haven’t decided on yet, which is how to deal with combining a device preset with a multistream file.
The biggest blocker currently for finishing this work is that the GStreamer encodebin element does not have an API yet for dealing with selecting encoding settings for multiple streams as detailed in this bug report. If anyone got the inclination to cook up a patch for encodebin which adds support for this that would be much appreciated.
Anyway, once I have this completed I think my next step will be to try to add some kind of DVD ripping support to Transmageddon and some basic metadata checking/editing and move the video flipping support into a special menu and add support for enabling/disabling deinterlacing in that same special menu. I trying to figure out as I go along how I can keep the user interface simple and straightforward and add requested features. The question that I continuously ask myself is what features do belong in Transmageddon and what features are of a level where people should go to something like PiTiVi instead.
Thanks to Sebastian Dröge there is a new thing in GStreamer called streamid. It basically gives all streams inside a given file a unique id, making files with multiple streams a lot easier to deal with. This streamid is also supported by the GStreamer discoverer object. So once you identified the contents of a file with discoverer you can be sure to grab the exact stream you want coming out of (uri)decodebin by checking the pad for the streamid. The most common usecase for this is of course files with multiple audio streams in different languages.
From the output of Discoverer the stream id is really easy to get:
On the stream object you get out of Discoverer you just run a:
On the pad you get from decodebin or uridecodebin the patch is a bit more convoluted, but not
to hard once you know how (there might be some kind of convenience API added for this at some point).
Before you connect the pad you get from the bin you attach a pad to it like this:
I been using this code in my local copy of Transmageddon to start implementing support for files with multiple audio streams (also supporting multiple video streams would be easy, but I am not sure how useful it would be). Got a screenshot of my current development snapshot below, but I am still trying to figure out what would be a nice way to present it. The current setup will look quite crap if the incoming file got more than a few audio streams. Suggestions welcome
GStreamer maintainer Wim Taymans decided that having a brand new GStreamer 1.x series was only worth the effort if we also had some nice up to date documentation for GStreamer 1.0. So over the last week he has been going over the GStreamer Application Development manual making sure it is up to date and fixing all the code examples and adding new chapters even. So if you want to get into GStreamer development our introduction manual should now be a good starting point again!
So I finally released an official new Transmageddon release today, 0.24. In addition to the changes from the 0.23 test release (GTK3 and GStreamer 1.0), this new version uses Python 3 and got some fixes for improved handling of missing codecs. Let me know if its giving you any trouble.
Next step is looking into how to implement some or all of the new interface design from Gendre Sébastien.
So this news is a couple of days old now, but I wanted to write a blog entry about the exciting release of GStreamer 1.0. When we released GStreamer 0.10 about 7 years ago we did not expect or plan the 0.10 series to last as long as it did, I think if we had it would have been called 1.0 instead of 0.10. Our caution back then was that 0.10 was a quite revolutionary version with the core of GStreamer extensively re-designed around effective use of threads and thread safety. The new GStreamer 1.0 is more of incremental improvement, cleaning up the API and making doing things modern systems expect easier and more straightforward. I think a lot of the work that went into 1.0 could be said to be based on cleaning up the awkward APIs that can evolve as you are not able to change anything existing, just add new stuff that does not affect the old.
That said there are a lot of major improvements to be seen too, with the list that Tim-Phillip Muller put together for the GStreamer website catching the major items:
more flexible memory handling
extensible and negotiable metadata for buffers
caps negotiation and renegotiation mechanisms, decoupled from buffer allocation
improved caps renegotiation
automatic re-sending of state for dynamic pipelines
reworked and more fine-grained pad probing
simpler and more descriptive audio and video caps
more efficient allocation of buffers, events and other mini objects
improved timestamp handling
support for gobject-inspection-based language bindings
The list can seem a bit technical and dry, but there are a lot of things that will benefit users here once plugins and applications start taking advantage of them. For instance the more flexible memory handling will improve performance when for instance running GStreamer on ARM boards like a Panda board or a Raspberry Pi. The changes will also make it a lot easier to write plugins and use plugins on PC platforms which use the GPU for decoding or encoding and that use OpenGL for rendering the playback. These things where possible with 0.10, but they required a bit more special casing and more code in the plugins and a bit more overhead in setting up the pipeline. If you want a great introduction to what is in this 1.0 release I recommend the keynote by Wim Taymans about GStreamer 1.0 and the GStreamer Status report keynote by Tim-Phillip Müller which both talk alot about the new features and the possibilities they open.
I think that the biggest change for a lot of developers though will be if they are using a language binding for their application, GStreamer 1.0 is offering Gobject introspection bindings support, which means that most bindings from now on will be using that. For Python developers like myself that is a quite big change in API. On the other hand it also does mean that porting to Python3 has become very simple. For Transmageddon I simply ran it through the Python 2to3 script and it just worked.
There are a lot of contributors to this release, and I would love to thank them all, but I think Wim and Tim also deserve a special mention as I don’t think there would be a GStreamer 1.0 without them. Wim has of course been the GStreamer maintainer for a long while and he shepherded this release from the beginning when he was the only developer working on it. Tim has been the GStreamer release manager for a long while now and are doing a wonderful job, fixing a gazillion bugs and making sure we regressions are not allowed to creep into GStreamer releases. He ended up doing a lot of heavy lifting to get the final GStreamer 0.11 test releases and the final 1.0 out the door. So a big big thanks to both of them.
Another person I want to give an extra kudos to is Bastien Nocera who have done a lot of working porting GNOME applications to GStreamer 1.0, there is and was of course a lot of other people involved in that process too, but Bastien did an incredible job working through that list and writing patches to port many of them over.
What I am really looking forward to now is the release of Fedora 18 as I think it will be the first chance for a lot of users and developers to try out all the great work that has been done on GStreamer 1.0 and porting applications over to it. I am personally targeting Fedora 18 with Transmageddon, doing my current testing and development on a F18 system, making sure things like the PackageKit integration is working smoothly.
I have made a first test release of Transmageddon today, 0.23. It is the first release depending on GStreamer 0.11/1.0 and GTK3. It also features a little bit of GNOME Shell and Unity integration in the form of a notification message when its done transcoding and the menu has been moved into the shell. You can find the test release in the pre-release directory on linuxrising.org. Let me know if you have any issues so I can try to fix them before I make a final stable release when GStreamer 1.0 is released. Be aware that you want the GStreamer 0.11 releases from yesterday to try this release.
The above screenshot is taken on my Fedora 18 test system!
Finally closed my slicehost account today and deleted my slice. I set it up a few years ago to host linuxrising.org and some misc other sites I was planning. I also hosted my own private email server on it.
In the end I think it just ended up being an overkill solution for what I really needed, but I thought it was a good experience to run my own server on the net. Anyway, Slicehost got bought by Rackspace some time ago and I kept getting these emails telling me to migrate to Rackspace and the rackspace priceplan. I took it as the kick I needed to get a hosting setup more suited to my actual need and save quite a bit of money in the process. So now the site is just hosted on my domain registrar as a simple website and the email I moved into Google Apps. At this point I am just happy I don’t have to fiddle with postfix and dovecot config files anytime in the forseeable future
While the DNS records etc. gets updated you might have some issues with the Transmageddon website, but it should hopefully be sorted before Monday.
New Transmageddon release should follow shortly after that.
As we count down towards the GStreamer 1.0 release I been spending some free moments preparing the new Transmageddon version, today I re-enabled multipass encoding, removed the redundant xvid option (as we already do MPEG4) and polished the notification message a little. Tried to run through with as many codecs as I can, and so far they all seem to work perfectly with GStreamer 1.0. So hopefully a new Transmageddon release soon
I think I got everything that was there before the 1.0 port back again, but I wouldn’t be surprised if I have managed to miss a feature somewhere
Heading off to Munich in an hour, but I been spending the morning trying to get git master transmageddon into shape. I think I am getting there as things works a lot better for me now. I even added a small feature, namely output to the notification area as seen in the screenshot below. Still very basic, but I hope to improve on it over the next few weeks. Also wondering if putting the Transmageddon nuclear mushroom in the notification area is a good way to keep users calm, or if they see the icon and start wondering if their system is suffering from a meltdown
Spent today working on Transmageddon, trying to get it ready for the GStreamer 1.0 release. It is frustrating going as I only get a little time here and there to work on it, and thus my memory of the code is not as good as it needs to be in order to do this efficiently. But I did in the end manage to file a couple of GStreamer 1.0 bug reports and restore the preset functionality to almost where it was before the GTK3/GStreamer 1.0 port.
When starting the port I disabled and removed a lot of code that in retrospect I still needed as I made some wrong assumptions about how encodebin would work. Going over the code now I also realize I have done some things in a quite stupid manner, or maybe the approaches made sense in the original codebase and just now over a series of iterations have become cludgy, anyway tried cleaning it up a bit, but didn’t have the time to really go over the code and make sure it looks nicer.
Of big issues remaining is that the missing codec functionality is still not 100% restored and working nicely, so a little more work needed there. But if you have all codecs already installed then things are shaping up quite nicely. So I think I am getting very close to having a GTK3 and GStreamer 1.0 version of Transmageddon at feature parity with the GTK2 and GStreamer 0.10 version.
Also thanks to Kalev Lember, Transmageddon is now in Fedora (the latest 0.10 based release) and he also made me co-maintainer of the package which I a very happy about. Hopefully this means that when Fedora switches to GStreamer 1.0 I can get the new Transmageddon up and running there quite quickly.
Also Gendre Sébastien plans on working on Transmageddon going forward and have already made some really cool mockups for a revamped UI. A lot of new features are planned, like the number one request I keep getting, support for setting up batches of transcoding jobs instead of having to do them one by one like now. My plan is to release a first version with the current UI and featureset for GTK3 and GStreamer 1.0, and then work with Gendre to implement his ideas. This new UI will also be more GNOME 3 styled, so hopefully it will provide users with something that feels more at home in the GNOME Shell and on Unity.
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