93 lines
3.4 KiB
Plaintext
93 lines
3.4 KiB
Plaintext
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PL_MPEG - MPEG1 Video decoder, MP2 Audio decoder, MPEG-PS demuxer
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Dominic Szablewski - https://phoboslab.org
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-- Synopsis
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// This function gets called for each decoded video frame
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void my_video_callback(plm_t *plm, plm_frame_t *frame, void *user) {
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// Do something with frame->y.data, frame->cr.data, frame->cb.data
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}
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// This function gets called for each decoded audio frame
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void my_audio_callback(plm_t *plm, plm_samples_t *frame, void *user) {
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// Do something with samples->interleaved
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}
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// Load a .mpg (MPEG Program Stream) file
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plm_t *plm = plm_create_with_filename("some-file.mpg");
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// Install the video & audio decode callbacks
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plm_set_video_decode_callback(plm, my_video_callback, my_data);
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plm_set_audio_decode_callback(plm, my_audio_callback, my_data);
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// Decode
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do {
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plm_decode(plm, time_since_last_call);
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} while (!plm_has_ended(plm));
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// All done
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plm_destroy(plm);
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-- Documentation
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This library provides several interfaces to load, demux and decode MPEG video
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and audio data. A high-level API combines the demuxer, video & audio decoders
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in an easy to use wrapper.
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Lower-level APIs for accessing the demuxer, video decoder and audio decoder,
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as well as providing different data sources are also available.
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Interfaces are written in an object orientet style, meaning you create object
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instances via various different constructor functions (plm_*create()),
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do some work on them and later dispose them via plm_*destroy().
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plm_* -- the high-level interface, combining demuxer and decoders
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plm_buffer_* -- the data source used by all interfaces
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plm_demux_* -- the MPEG-PS demuxer
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plm_video_* -- the MPEG1 Video ("mpeg1") decoder
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plm_audio_* -- the MPEG1 Audio Layer II ("mp2") decoder
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This library uses malloc(), realloc() and free() to manage memory. Typically
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all allocation happens up-front when creating the interface. However, the
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default buffer size may be too small for certain inputs. In these cases plmpeg
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will realloc() the buffer with a larger size whenever needed. You can configure
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the default buffer size by defining PLM_BUFFER_DEFAULT_SIZE *before*
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including this library.
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With the high-level interface you have two options to decode video & audio:
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1) Use plm_decode() and just hand over the delta time since the last call.
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It will decode everything needed and call your callbacks (specified through
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plm_set_{video|audio}_decode_callback()) any number of times.
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2) Use plm_decode_video() and plm_decode_audio() to decode exactly one
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frame of video or audio data at a time. How you handle the synchronization of
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both streams is up to you.
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If you only want to decode video *or* audio through these functions, you should
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disable the other stream (plm_set_{video|audio}_enabled(false))
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Video data is decoded into a struct with all 3 planes (Y, Cr, Cb) stored in
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separate buffers. You can either convert this to RGB on the CPU (slow) via the
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plm_frame_to_rgb() function or do it on the GPU with the following matrix:
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mat4 rec601 = mat4(
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1.16438, 0.00000, 1.59603, -0.87079,
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1.16438, -0.39176, -0.81297, 0.52959,
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1.16438, 2.01723, 0.00000, -1.08139,
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0, 0, 0, 1
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);
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gl_FragColor = vec4(y, cb, cr, 1.0) * rec601;
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Audio data is decoded into a struct with either one single float array with the
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samples for the left and right channel interleaved, or if the
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PLM_AUDIO_SEPARATE_CHANNELS is defined *before* including this library, into
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two separate float arrays - one for each channel.
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See below for detailed the API documentation.
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