Etheora

Etheora is a a simplified API for programming Theora video encoding/decoding applications with Ogg containers. It uses and encapsulates libtheora + libogg API and structures, so users need to know very few about video and data containers.

Overview - Encoding

An encoding process is made by these steps:

/* a context declaration. */
etheora_ctx ec;

/* encoder configuration. */
etheora_enc_setup(&ec, width, height, ETHEORA_ASPECT_NORMAL,
fopen("output-video.ogv"), fopen("debug_info.txt"));

/* encoder start. */
etheora_enc_start(&ec);

/* drawing next frame, by puting a r,g,b or y,u,v pixel in (i,j) coordinate */
etheora_enc_rgb_draw(&ec, i, j, r, g, b);
/* alternative: etheora_enc_yuv_draw()) */

/* submiting frame to encoding. */
etheora_enc_nextframe(&ec);

/* submiting last frame to encoding by finishing the process. */
etheora_enc_finish(&ec);

The functions _yuv_ and _rgb_ works transparently with OC_PF_420, OC_PF_422 and OC_PF_PF_444, having the libtheora version used support for them or not.

Overview - Decoding

The decoding process is quite similar.

/* a context declaration. */
etheora_ctx ec;

/* decoder configuration. */
etheora_dec_setup(&ec, fopen("input-video.ogv"), fopen("debug_info.txt")); 

/* decoder start. */
etheora_dec_start(&ec); 

/* reading video data. */
etheora_get_width(&ec);
etheora_get_heigth(&ec);
etheora_get_fps_numerator(&ec);
etheora_get_fps_denominator(&ec);
etheora_get_aspect_numerator(&ec);
etheora_get_aspect_denominator(&ec);

/* getting next frame by decoding it. */
etheora_dec_nextframe(&ec); 

/* getting frame data, by reading a r,g,b or y,u,v pixel in (i,j) coordinate*/
etheora_dec_rgb_read(&ec, i, j, &r, &g, &b)
/* alternative: etheora_dec_yuv_read()) */

/* finishing the process. */
etheora_dec_finish(&ec);

The functions _yuv_ and _rgb_ works transparently with OC_PF_420, OC_PF_422 and OC_PF_PF_444, having the libtheora version used support for them or not.

Overview - Going Further

Etheora is documented here: http://svn.xiph.org/branches/etheora-0.1.1/doc/etheora_documentation.pdf

Etheora code is here: http://svn.xiph.org/branches/etheora-0.1.1/src/

Etheora very simple examples are found here: http://svn.xiph.org/branches/etheora-0.1.1/examples/

Etheora still doesn't have audio/speech support. (Although it can get video data from videos with audio). And uses internally the old libtheora API (ie, not the theora-exp). FIXME: The theora-exp API is what's used now on libtheora 1.0. Please use that API instead.

TODO

• Vorbis support
• Speex support
• Skeleton support

See also

• Theora Hardware: List of hardware-players supporting Ogg Theora
• TheoraSoftwarePlayers: List of media players that can play Ogg Theora
• TheoraSoftwareEncoders: List of software that can encode to Ogg Theora
• TheoraDecoders: List of decoder implementations
• TheoraEncoders: List of encoder implementations
• List of Theora videos: Get some files to see what the codec's like
• Games that use Theora: List of known games that use Theora
• TheoraTestsuite: Different samples to test player compliance