From 150c9823e71a161e97003849cf8b2f55b21520bd Mon Sep 17 00:00:00 2001 From: Tim Redfern Date: Mon, 26 Aug 2013 15:10:18 +0100 Subject: adding ffmpeg specific version --- ffmpeg1/libavcodec/rtjpeg.c | 173 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 173 insertions(+) create mode 100644 ffmpeg1/libavcodec/rtjpeg.c (limited to 'ffmpeg1/libavcodec/rtjpeg.c') diff --git a/ffmpeg1/libavcodec/rtjpeg.c b/ffmpeg1/libavcodec/rtjpeg.c new file mode 100644 index 0000000..fe781ce --- /dev/null +++ b/ffmpeg1/libavcodec/rtjpeg.c @@ -0,0 +1,173 @@ +/* + * RTJpeg decoding functions + * Copyright (c) 2006 Reimar Doeffinger + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include "libavutil/common.h" +#include "get_bits.h" +#include "rtjpeg.h" + +#define PUT_COEFF(c) \ + i = scan[coeff--]; \ + block[i] = (c) * quant[i]; + +/// aligns the bitstream to the given power of two +#define ALIGN(a) \ + n = (-get_bits_count(gb)) & (a - 1); \ + if (n) {skip_bits(gb, n);} + +/** + * @brief read one block from stream + * @param gb contains stream data + * @param block where data is written to + * @param scan array containing the mapping stream address -> block position + * @param quant quantization factors + * @return 0 means the block is not coded, < 0 means an error occurred. + * + * Note: GetBitContext is used to make the code simpler, since all data is + * aligned this could be done faster in a different way, e.g. as it is done + * in MPlayer libmpcodecs/native/rtjpegn.c. + */ +static inline int get_block(GetBitContext *gb, int16_t *block, const uint8_t *scan, + const uint32_t *quant) { + int coeff, i, n; + int8_t ac; + uint8_t dc = get_bits(gb, 8); + + // block not coded + if (dc == 255) + return 0; + + // number of non-zero coefficients + coeff = get_bits(gb, 6); + if (get_bits_left(gb) < (coeff << 1)) + return -1; + + // normally we would only need to clear the (63 - coeff) last values, + // but since we do not know where they are we just clear the whole block + memset(block, 0, 64 * sizeof(int16_t)); + + // 2 bits per coefficient + while (coeff) { + ac = get_sbits(gb, 2); + if (ac == -2) + break; // continue with more bits + PUT_COEFF(ac); + } + + // 4 bits per coefficient + ALIGN(4); + if (get_bits_left(gb) < (coeff << 2)) + return -1; + while (coeff) { + ac = get_sbits(gb, 4); + if (ac == -8) + break; // continue with more bits + PUT_COEFF(ac); + } + + // 8 bits per coefficient + ALIGN(8); + if (get_bits_left(gb) < (coeff << 3)) + return -1; + while (coeff) { + ac = get_sbits(gb, 8); + PUT_COEFF(ac); + } + + PUT_COEFF(dc); + return 1; +} + +/** + * @brief decode one rtjpeg YUV420 frame + * @param c context, must be initialized via ff_rtjpeg_decode_init + * @param f AVFrame to place decoded frame into. If parts of the frame + * are not coded they are left unchanged, so consider initializing it + * @param buf buffer containing input data + * @param buf_size length of input data in bytes + * @return number of bytes consumed from the input buffer + */ +int ff_rtjpeg_decode_frame_yuv420(RTJpegContext *c, AVFrame *f, + const uint8_t *buf, int buf_size) { + GetBitContext gb; + int w = c->w / 16, h = c->h / 16; + int x, y; + uint8_t *y1 = f->data[0], *y2 = f->data[0] + 8 * f->linesize[0]; + uint8_t *u = f->data[1], *v = f->data[2]; + init_get_bits(&gb, buf, buf_size * 8); + for (y = 0; y < h; y++) { + for (x = 0; x < w; x++) { +#define BLOCK(quant, dst, stride) do { \ + int res = get_block(&gb, block, c->scan, quant); \ + if (res < 0) \ + return res; \ + if (res > 0) \ + c->dsp->idct_put(dst, stride, block); \ +} while (0) + int16_t *block = c->block; + BLOCK(c->lquant, y1, f->linesize[0]); + y1 += 8; + BLOCK(c->lquant, y1, f->linesize[0]); + y1 += 8; + BLOCK(c->lquant, y2, f->linesize[0]); + y2 += 8; + BLOCK(c->lquant, y2, f->linesize[0]); + y2 += 8; + BLOCK(c->cquant, u, f->linesize[1]); + u += 8; + BLOCK(c->cquant, v, f->linesize[2]); + v += 8; + } + y1 += 2 * 8 * (f->linesize[0] - w); + y2 += 2 * 8 * (f->linesize[0] - w); + u += 8 * (f->linesize[1] - w); + v += 8 * (f->linesize[2] - w); + } + return get_bits_count(&gb) / 8; +} + +/** + * @brief initialize an RTJpegContext, may be called multiple times + * @param c context to initialize + * @param dsp specifies the idct to use for decoding + * @param width width of image, will be rounded down to the nearest multiple + * of 16 for decoding + * @param height height of image, will be rounded down to the nearest multiple + * of 16 for decoding + * @param lquant luma quantization table to use + * @param cquant chroma quantization table to use + */ +void ff_rtjpeg_decode_init(RTJpegContext *c, DSPContext *dsp, + int width, int height, + const uint32_t *lquant, const uint32_t *cquant) { + int i; + c->dsp = dsp; + for (i = 0; i < 64; i++) { + int z = ff_zigzag_direct[i]; + int p = c->dsp->idct_permutation[i]; + z = ((z << 3) | (z >> 3)) & 63; // rtjpeg uses a transposed variant + + // permute the scan and quantization tables for the chosen idct + c->scan[i] = c->dsp->idct_permutation[z]; + c->lquant[p] = lquant[i]; + c->cquant[p] = cquant[i]; + } + c->w = width; + c->h = height; +} -- cgit v1.2.3