68 строки
2.9 KiB
Plaintext
68 строки
2.9 KiB
Plaintext
@TEMPLATE decoder_tmpl.c
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Postprocessing Decoder
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======================
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION
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This example adds postprocessing to the simple decoder loop.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION
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Initializing Postprocessing
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---------------------------
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You must inform the codec that you might request postprocessing at
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initialization time. This is done by passing the VPX_CODEC_USE_POSTPROC
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flag to `vpx_codec_dec_init`. If the codec does not support
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postprocessing, this call will return VPX_CODEC_INCAPABLE. For
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demonstration purposes, we also fall back to default initialization if
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the codec does not provide support.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC_INIT
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/* Initialize codec */
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res = vpx_codec_dec_init(&codec, interface, NULL,
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VPX_CODEC_USE_POSTPROC);
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if(res == VPX_CODEC_INCAPABLE) {
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printf("NOTICE: Postproc not supported by %s\n",
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vpx_codec_iface_name(interface));
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res = vpx_codec_dec_init(&codec, interface, NULL, flags);
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}
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if(res)
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die_codec(&codec, "Failed to initialize decoder");
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC_INIT
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Using Adaptive Postprocessing
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-----------------------------
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VP6 provides "adaptive postprocessing." It will automatically select the
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best postprocessing filter on a frame by frame basis based on the amount
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of time remaining before the user's specified deadline expires. The
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special value 0 indicates that the codec should take as long as
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necessary to provide the best quality frame. This example gives the
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codec 15ms (15000us) to return a frame. Remember that this is a soft
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deadline, and the codec may exceed it doing its regular processing. In
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these cases, no additional postprocessing will be done.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DECODE
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/* Decode the frame with 15ms deadline */
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if(vpx_codec_decode(&codec, frame, frame_sz, NULL, 15000))
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die_codec(&codec, "Failed to decode frame");
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DECODE
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Codec Specific Postprocessing Controls
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--------------------------------------
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Some codecs provide fine grained controls over their built-in
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postprocessors. VP8 is one example. The following sample code toggles
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postprocessing on and off every 15 frames.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PRE_DECODE
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#if CONFIG_VP9_DECODER
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if(frame_cnt%30 == 1) {
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vp8_postproc_cfg_t pp = {0, 0, 0};
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if(vpx_codec_control(&codec, VP8_SET_POSTPROC, &pp))
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die_codec(&codec, "Failed to turn off postproc");
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} else if(frame_cnt%30 == 16) {
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vp8_postproc_cfg_t pp = {VP8_DEBLOCK | VP8_DEMACROBLOCK | VP8_MFQE, 4, 0};
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if(vpx_codec_control(&codec, VP8_SET_POSTPROC, &pp))
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die_codec(&codec, "Failed to turn on postproc");
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};
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#endif
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PRE_DECODE
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