Emscripten is an LLVM-to-JavaScript compiler. It takes LLVM bitcode - which
can be generated from C/C++, using llvm-gcc or clang, or any other language
that can be converted into LLVM - and compiles that into JavaScript, which
can be run on the web (or anywhere else JavaScript can run).
I was able to successfully build libogg, libvorbis and libvorbis examples
using this tool and generate valid JavaScript (hopefully working as
intended also...).
In JavaScript, once I obtain the left and right channel audio data (using
W3C web audio api) I pass this data into the JavaScript encoder as command
line arguments. This data is then read, each string converted to a float,
and the vorbis_analysis_buffer is filled with this "parsed" data.
Similarly, I pass the quality as an argument and run vorbis_encode_init_vbr
accordingly.
One last thing that I pass in is a "state" of a stream - either the
beginning, middle, or end so I can handle these cases differently (for
example, at the start of the stream I set all necessary headers).
The generated file, however, does not seem to be valid and does not play.
Could somebody verify that my encoding logic is sound? Here is the C source
on GitHub (based on libvorbis encoder_example.c) :
github.com/mateusz-/vorbisenc.js/blob/master/encoder_example.c
And, if it helps, here is the corrupted/invalid Ogg file :
raw.github.com/mateusz-/vorbisenc.js/master/audio.ogg
Thank you,
Mateusz
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Hello,<div><br></div><div>First of all, I am a complete
newblet to anything dealing with audio (a lot of the vocabulary is still rather
mysterious to me). I also don't often program in C so please
don't throw too many stones if my workflow is less than ideal.
:)</div>
<div><br></div><div>I would like to port the vorbis
encoder to JavaScript. Instead of porting everything by hand from ground up,
which would take who-knows-how-long, I am using a tool called emscripten (<a
href=3D"github.com/kripken/emscripten"
target=3D"_blank">github.com/kripken/emscripten</a>).
From the docs:</div>
<div><br></div><div>Emscripten is an LLVM-to-JavaScript
compiler. It takes LLVM bitcode - which can be generated from C/C++, using
llvm-gcc or clang, or any other language that can be converted into LLVM - and
compiles that into JavaScript, which can be run on the web (or anywhere else
JavaScript can run).</div>
<div><br></div><div>I was able to successfully build
libogg, libvorbis and libvorbis examples using this tool and generate valid
JavaScript (hopefully working as intended
also...).</div><div><br></div><div>
In JavaScript, once I obtain the left and right channel audio data (using W3C
web audio api) I pass this data into the JavaScript encoder as command line
arguments. This data is then read, each string converted to a float, and the
vorbis_analysis_buffer is filled with this "parsed" data.
Similarly, I pass the quality as an argument and run vorbis_encode_init_vbr
accordingly.</div>
<div><br></div><div>One last thing that I pass in is a
"state" of a stream - either the beginning, middle, or end so
I can handle these cases differently (for example, at the start of the stream I
set all necessary headers).</div>
<div><br></div><div>The generated file, however, does
not seem to be valid and does not
play.</div><div><br></div><div>Could somebody
verify that my encoding logic is sound? Here is the C source on GitHub (based on
libvorbis encoder_example.c) :=A0<a
href=3D"github.com/mateusz-/vorbisenc.js/blob/master/encoder_example.c">github.com/mateusz-/vorbisenc.js/blob/master/encoder_example.c</a></div>
<div>
And, if it helps, here is the corrupted/invalid Ogg file :=A0<a
href=3D"raw.github.com/mateusz-/vorbisenc.js/master/audio.ogg">raw.github.com/mateusz-/vorbisenc.js/master/audio.ogg</a></div><div><br></div><div>
Thank you,</div><div>Mateusz</div>
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