Transcode 1.0.2 review

Transcode is a suite of command line utilities for transcoding video and audio codecs, and for converting beween different container

License: GPL (GNU General Public License) File size: 0K Developer: Transcode Team

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Transcode is a suite of command line utilities for transcoding video and audio codecs, and for converting beween different container formats. Transcode can decode and encode many audio and video formats, e.g.

MPEG-1/2
MPEG-4(-part 3) (also DivX and XviD variants)
Quicktime / MPEG-PS (dvd) (decode only)
MPEG-1-layer-1/2/3 audio
AC3 audio

Transcode has a variety of video and audio pre and post-processing filters, including (but not limited to):

video de-interlacing
audio resampling
framerate conversion
smoothing
cutting

Transcode can import DVDs on-the-fly, or record from Video4Linux (including V4L2 video capturing) devices.

A number of modules are included to enable import of DVDs on-the-fly, Video4Linux (including V4L2 video capturing), MPEG elementary streams (ES) or program streams (VOB), MPEG1/2/4 video, Digital Video (DV), YUV4MPEG streams, Nuppel Video (NUV), quicktime (MOV), MPEG audio layer-1/2/3, WAVE, DIVX, MJPEG, and raw or compressed (pass-through) video frames.

A number of export modules for enable writing DivX ;-), DivX 4.02/5.xx, XviD, Digital Video, MPEG-1/2 or uncompressed AVI files with MPEG, AC3 (pass-through) or PCM audio. More file formats and codecs for audio/video import are supported by the MPlayer and avifile import modules (exporting with avifile is restricted to video codecs, with MPEG/PCM or AC3 (pass-through) audio provided by transcode). Limited DVD subtitle rendering is also available.

Its modular concept is intended to provide flexibility and easy user extensibility to include other video/audio codecs or file types. A set of tools is available to extract, demultiplex and decode the sources into raw video/audio streams for import, non AVI-file export modules for writing single frames (PPM) or YUV4MPEG streams, auto-probing and scanning your sources and to enable post-processing of AVI files, including header fixing, merging multiple files or splitting large AVI files to fit on a CD.
Transcode runs on UN*X like systems like Linux, BSD, and MacOSX.

Transcode loads shared library modules that are responsible for feeding it with raw streams and encoding the frames:

The Import Modules for audio/video decoding are loaded with dlopen system call and are responsible for starting the video and audio streams (directly or via the popen system call) and have a single function interface to the main program. The import is handled by a thread that buffers the video/audio frames.
The main program transcode currently performs a number of simple video/audio frame manipulations (in this order) or allows simple pass-through of raw frame data:

Video:

cut out arbitray frame region for processing
de-interlace video frame
fast enlarging of video width/height by a multiple of 32 rows/column up to 1024x768
fast reduction of video width/height by a multiple of 32 rows/column
high-quality resizing with filter
cut out arbitray frame region for encoding
rescale (downsample) video width/height by a power of 2
flip video frame upside down
mirror image of video frame
swap R and B bytes in video frame
transform to b/w video frame
apply gamma correction
anti-alias video frame

Audio:

change the volume of the audio stream
resample audio stream
swap byte order in audio stream
sync video with audio frames (V=0|A=N, V=1|A=N+1,...)
Filter Plugins:
Additional effects are available via external filter plugins loaded with option "-J".

The Export Modules for audio/video encoding are loaded via the dlopen system call and the encoder loop is started for the selected frames. In most cases audio and video are handled by the same module.