------------------------------------------------------------------------- This README file is up to date with and covers Xiph.Org's first alpha release of the Theora video codec on 25 09 2002. ------------------------------------------------------------------------- *** What is Theora? Theora is Xiph.Org's first publicly released video codec, intended for use within the Ogg's project's Ogg multimedia streaming system. Theora is derived directly from On2's VP3 codec; Currently the two are nearly identical, varying only in framing headers, but Theora will diverge and improve from the main VP3 development lineage as time progresses. *** Where is Theora? Theora's main site is www.theora.org. Theora and related libraries can be gotten from www.theora.org or the main Xiph.Org site at www.xiph.org. In order to access CVS at xiph.org (the best way to get to the source), see http://www.xiph.org/cvs.html *** What is the goal of this alpha release? This alpha is a proof of concept, not a production-ready release. Do not expect the Theora packet or stream format from this release to remain compatible with future releases. When the format for Theora is officially frozen, we'll let you know. This release serves several purposes: 1) An initial, thorough code review of the current VP3 implementation as we begin the transition to Theora. We sum the results of the VP3 review below: . Fixed [on the order of] fifty bugs capable of crashing the codec during encode, playback or both. . More thorough review of the codebase is warranted; however most immediately indicated work has been covered in initial review. . Xiph.Org has substantially bootstrapped the imported codebase and is ready to support Theora. . Performance of unoptimized, pure-C version of VP3/Theora is very good. 2) Proof of concept: The example programs included in Theora/examples implement a mixed-stream (Theora/Vorbis) Ogg encoder and player. These applications, though simple, show Ogg functioning as intended as a full multimedia container, illustrate the beginning of VP3/Theora integration into Ogg and showcase the current level of performance of the portable, unoptimized C implementation of Theora in terms of speed, quality and bitrate. 3) Initial implementation testing; this release serves as both a testbed and a public request for input. Once more for the record: THIS RELEASE IS NOT PRODUCTION CODE. It is not for ripping DVDs, writing a Xine/MPlayer plugin or anything beyond tinkering. The Theora stream format WILL CHANGE in future releases. The API WILL CHANGE. We will not yet support any Theora files produced by this alpha. Not yet. Soon, Grasshopper, Soon. ------------------------------------------------------------------------- Getting started with the code ------------------------------------------------------------------------- *** What do I need to build the source? Requirements summary: For libtheora: libogg dated 24092002 or newer, built and installed from Xiph.Org CVS GNU automake/autoconf/libtool build utilities For example encoder: as above libvorbis and libvorbisenc dated 24092002 or newer, built and installed from Xiph.Org CVS For the player only: as above, SDL (Simple Direct media Layer) libraries and headers OSS audio driver and development headers This release is brand new and full portability is still in progress. The provided build system is the GNU automake/autoconf system, and the main library, libtheora, should already build smoothly on any system. Failure of libtheora to build on a GNU-enabled system is considered a bug; please report problems to theora-dev@xiph.org. *** How do I use the sample encoder? The sample encoder takes raw video in YUV4MPEG2 format, as used by lavtools, mjpeg-tools and other packages. Snatch and MPlayer version 0.90 and later can also export in YUV4MPEG format (more on this later). The encoder take audio as WAV files. encoder_example -h lists options accepted by the encoder. An easy way to get raw video and audio files is to use MPlayer as an export utility. The options " -ao pcm -vo yuv4mpeg " will export a wav vile named audiodump.wav and a YUV video file in the correct format for encoder_example as stream.yuv. Be careful when exporting video alone; MPlayer may drop frames to 'keep up' with the audio timer. The example encoder can't properly synchronize input audio and video file that aren't in sync to begin with. The encoder will also take video or audio on stdin if '-' is specified as the input file name. *** How do I use the sample player? The sample player takes an Ogg file on standard in; the file may be audio alone, video alone or video with audio. ------------------------------------------------------------------------- Troubleshooting the build process ------------------------------------------------------------------------- *** Compile error, such as: encoder_internal.h:664: parse error before `ogg_uint16_t' A *complete* new Ogg install, libs and headers, from CVS really is needed. Don't forget to re-reun autogen.sh so that autoconf sucks in the new type declarations. Also be sure that there aren't multiple copies of Ogg installed in /usr and /usr/local; an older one might be first on the search path for libs and headers. *** Link error, such as: undefined reference to `oggpackB_stream' See above; you need libogg from CVS. *** Link error, such as: undefined reference to `vorbis_granule_time' You need libvorbis and libvorbisenc from CVS. *** Link error, such as: /usr/lib/libSDL.a(SDL_esdaudio.lo): In function `ESD_OpenAudio': SDL_esdaudio.lo(.text+0x25d): undefined reference to `esd_play_stream' Be sure to use an SDL that's built to work with OSS. If you use an SDL that is also built with ESD and/or ALSA support, it will try to suck in all those extra libraries at link time too. That will only work if the extra libraries are also installed. *** Link warning, such as: libtool: link: warning: library `/usr/lib/libogg.la' was moved. libtool: link: warning: library `/usr/lib/libogg.la' was moved. Re-run theora/autogen.sh after an Ogg or Vorbis rebuild/reinstall