Add CPiA video decoder

The cpia video decoder is intended to be used with the v4l2 demuxer.
There are some small changes to the v4l2 demuxer to support the
variable frame length of the format.
Fixes ticket #1537

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 218 insertions, 0 deletions

diff --git a/libavcodec/cpia.c b/libavcodec/cpia.c
new file mode 100644
index 0000000000..c45936b65f
--- /dev/null
+++ b/libavcodec/cpia.c
@@ -0,0 +1,218 @@
+/*
+ * CPiA video decoder.
+ * Copyright (c) 2010 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This decoder is based on the LGPL code available at
+ * https://v4l4j.googlecode.com/svn/v4l4j/trunk/libvideo/libv4lconvert/cpia1.c
+ *
+ * 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 "avcodec.h"
+#include "get_bits.h"
+
+
+#define FRAME_HEADER_SIZE 64
+#define MAGIC_0         0x19    /**< First header byte */
+#define MAGIC_1         0x68    /**< Second header byte */
+#define SUBSAMPLE_420      0
+#define SUBSAMPLE_422      1
+#define YUVORDER_YUYV      0
+#define YUVORDER_UYVY      1
+#define NOT_COMPRESSED     0
+#define COMPRESSED         1
+#define NO_DECIMATION      0
+#define DECIMATION_ENAB    1
+#define EOL             0xfd    /**< End Of Line marker */
+#define EOI             0xff    /**< End Of Image marker */
+
+
+typedef struct {
+    AVFrame frame;
+} CpiaContext;
+
+
+static int cpia_decode_frame(AVCodecContext* avctx,
+        void* data, int* data_size, AVPacket* avpkt)
+{
+    CpiaContext* const cpia = avctx->priv_data;
+    int i,j,ret;
+
+    uint8_t* const header = avpkt->data;
+    uint8_t* src;
+    int src_size;
+    uint16_t linelength;
+    uint8_t skip;
+
+    AVFrame* const frame = &cpia->frame;
+    uint8_t *y, *u, *v, *y_end, *u_end, *v_end;
+
+    // Get buffer filled with previous frame
+    if ((ret = avctx->reget_buffer(avctx, frame)) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed!\n");
+        return ret;
+    }
+
+    // Check header
+    if ( avpkt->size < FRAME_HEADER_SIZE
+      || header[0] != MAGIC_0 || header[1] != MAGIC_1
+      || (header[17] != SUBSAMPLE_420 && header[17] != SUBSAMPLE_422)
+      || (header[18] != YUVORDER_YUYV && header[18] != YUVORDER_UYVY)
+      || (header[28] != NOT_COMPRESSED && header[28] != COMPRESSED)
+      || (header[29] != NO_DECIMATION && header[29] != DECIMATION_ENAB)
+    ) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid header!\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    // currently unsupported properties
+    if (header[17] == SUBSAMPLE_422) {
+        av_log(avctx, AV_LOG_ERROR, "Unsupported subsample!\n");
+        return AVERROR_PATCHWELCOME;
+    }
+    if (header[18] == YUVORDER_UYVY) {
+        av_log(avctx, AV_LOG_ERROR, "Unsupported YUV byte order!\n");
+        return AVERROR_PATCHWELCOME;
+    }
+    if (header[29] == DECIMATION_ENAB) {
+        av_log(avctx, AV_LOG_ERROR, "Decimation unsupported!\n");
+        return AVERROR_PATCHWELCOME;
+    }
+
+    src = header + FRAME_HEADER_SIZE;
+    src_size = avpkt->size - FRAME_HEADER_SIZE;
+
+    if (header[28] == NOT_COMPRESSED) {
+        frame->pict_type = AV_PICTURE_TYPE_I;
+        frame->key_frame = 1;
+    } else {
+        frame->pict_type = AV_PICTURE_TYPE_P;
+        frame->key_frame = 0;
+    }
+
+
+    for ( i = 0;
+          i < frame->height;
+          i++, src += linelength, src_size -= linelength
+    ) {
+        // Read line length, two byte little endian
+        linelength = AV_RL16(src);
+        src += 2;
+
+        if (src_size < linelength) {
+            frame->decode_error_flags = FF_DECODE_ERROR_INVALID_BITSTREAM;
+            av_log(avctx, AV_LOG_WARNING, "Frame ended enexpectedly!\n");
+            break;
+        }
+        if (src[linelength - 1] != EOL) {
+            frame->decode_error_flags = FF_DECODE_ERROR_INVALID_BITSTREAM;
+            av_log(avctx, AV_LOG_WARNING, "Wrong line length %d or line not terminated properly (found 0x%02x)!\n", linelength, src[linelength - 1]);
+            break;
+        }
+
+        /* Update the data pointers. Y data is on every line.
+         * U and V data on every second line
+         */
+        y = &frame->data[0][i * frame->linesize[0]];
+        u = &frame->data[1][(i >> 1) * frame->linesize[1]];
+        v = &frame->data[2][(i >> 1) * frame->linesize[2]];
+        y_end = y + frame->linesize[0] - 1;
+        u_end = u + frame->linesize[1] - 1;
+        v_end = v + frame->linesize[2] - 1;
+
+        if ((i & 1) && header[17] == SUBSAMPLE_420) {
+            /* We are on a odd line and 420 subsample is used.
+             * On this line only Y values are specified, one per pixel.
+             */
+            for (j = 0; j < linelength - 1; j++) {
+                if (y > y_end) {
+                    frame->decode_error_flags = FF_DECODE_ERROR_INVALID_BITSTREAM;
+                    av_log(avctx, AV_LOG_WARNING, "Decoded data exceeded linesize!\n");
+                    break;
+                }
+                if ((src[j] & 1) && header[28] == COMPRESSED) {
+                    /* It seems that odd lines are always uncompressed, but
+                     * we do it according to specification anyways.
+                     */
+                    skip = src[j] >> 1;
+                    y += skip;
+                } else {
+                    *(y++) = src[j];
+                }
+            }
+        } else if (header[17] == SUBSAMPLE_420) {
+            /* We are on an even line and 420 subsample is used.
+             * On this line each pair of pixels is described by four bytes.
+             */
+            for (j = 0; j < linelength - 4; ) {
+                if (y + 1 > y_end || u > u_end || v > v_end) {
+                    frame->decode_error_flags = FF_DECODE_ERROR_INVALID_BITSTREAM;
+                    av_log(avctx, AV_LOG_WARNING, "Decoded data exceeded linesize!\n");
+                    break;
+                }
+                if ((src[j] & 1) && header[28] == COMPRESSED) {
+                    // Skip amount of pixels and move forward one byte
+                    skip = src[j] >> 1;
+                    y += skip;
+                    u += skip >> 1;
+                    v += skip >> 1;
+                    j++;
+                } else {
+                    // Set image data as specified and move forward 4 bytes
+                    *(y++) = src[j];
+                    *(u++) = src[j+1];
+                    *(y++) = src[j+2];
+                    *(v++) = src[j+3];
+                    j += 4;
+                }
+            }
+        }
+    }
+
+    *data_size = sizeof(AVFrame);
+    *(AVFrame*) data = *frame;
+
+    return avpkt->size;
+}
+
+static av_cold int cpia_decode_init(AVCodecContext *avctx)
+{
+    // output pixel format
+    avctx->pix_fmt = PIX_FMT_YUV420P;
+
+    /* The default timebase set by the v4l2 demuxer leads to probing which is buggy.
+     * Set some reasonable time_base to skip this.
+     */
+    if (avctx->time_base.num == 1 && avctx->time_base.den == 1000000) {
+        avctx->time_base.num = 1;
+        avctx->time_base.den = 60;
+    }
+
+    return 0;
+}
+
+
+AVCodec ff_cpia_decoder = {
+    .name           = "cpia",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_CPIA,
+    .priv_data_size = sizeof(CpiaContext),
+    .init           = cpia_decode_init,
+    .decode         = cpia_decode_frame,
+    .capabilities   = CODEC_CAP_DR1,
+    .long_name      = NULL_IF_CONFIG_SMALL("CPiA video format"),
+};