Screenpresso SPV1 decoder

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

1 files changed, 186 insertions, 0 deletions

diff --git a/libavcodec/screenpresso.c b/libavcodec/screenpresso.c
new file mode 100644
index 0000000000..d25d0ebb9d
--- /dev/null
+++ b/libavcodec/screenpresso.c
@@ -0,0 +1,186 @@
+/*
+ * Screenpresso decoder
+ * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Screenpresso decoder
+ *
+ * Fourcc: SPV1
+ *
+ * Screenpresso simply horizontally flips and then deflates frames,
+ * alternating full pictures and deltas. Deltas are related to the currently
+ * rebuilt frame (not the reference), and since there is no coordinate system
+ * they contain exactly as many pixel as the keyframe.
+ *
+ * Supports: BGR24
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <zlib.h>
+
+#include "libavutil/imgutils.h"
+#include "libavutil/internal.h"
+
+#include "avcodec.h"
+#include "internal.h"
+
+typedef struct ScreenpressoContext {
+    AVFrame *current;
+
+    /* zlib interation */
+    uint8_t *inflated_buf;
+    uLongf inflated_size;
+} ScreenpressoContext;
+
+static av_cold int screenpresso_close(AVCodecContext *avctx)
+{
+    ScreenpressoContext *ctx = avctx->priv_data;
+
+    av_frame_free(&ctx->current);
+    av_freep(&ctx->inflated_buf);
+
+    return 0;
+}
+
+static av_cold int screenpresso_init(AVCodecContext *avctx)
+{
+    ScreenpressoContext *ctx = avctx->priv_data;
+
+    /* These needs to be set to estimate uncompressed buffer */
+    int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid image size %dx%d.\n",
+               avctx->width, avctx->height);
+        return ret;
+    }
+
+    /* Allocate current frame */
+    ctx->current = av_frame_alloc();
+    if (!ctx->current)
+        return AVERROR(ENOMEM);
+
+    avctx->pix_fmt = AV_PIX_FMT_BGR24;
+
+    return 0;
+}
+
+static void sum_delta_flipped(uint8_t       *dst, int dst_linesize,
+                              const uint8_t *src, int src_linesize,
+                              int bytewidth, int height)
+{
+    int i;
+    for (; height > 0; height--) {
+        for (i = 0; i < bytewidth; i++)
+            dst[i] += src[(height - 1) * src_linesize + i];
+        dst += dst_linesize;
+    }
+}
+
+static int screenpresso_decode_frame(AVCodecContext *avctx, void *data,
+                                     int *got_frame, AVPacket *avpkt)
+{
+    ScreenpressoContext *ctx = avctx->priv_data;
+    AVFrame *frame = data;
+    int keyframe;
+    int ret;
+
+    /* Size check */
+    if (avpkt->size < 3) {
+        av_log(avctx, AV_LOG_ERROR, "Packet too small (%d)\n", avpkt->size);
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* Basic sanity check, but not really harmful */
+    if ((avpkt->data[0] != 0x73 && avpkt->data[0] != 0x72) ||
+        avpkt->data[1] != 8) { // bpp probably
+        av_log(avctx, AV_LOG_WARNING, "Unknown header 0x%02X%02X\n",
+               avpkt->data[0], avpkt->data[1]);
+    }
+    keyframe = (avpkt->data[0] == 0x73);
+
+    /* Resize deflate buffer and frame on resolution change */
+    if (ctx->inflated_size != avctx->width * avctx->height * 3) {
+        av_frame_unref(ctx->current);
+        ret = ff_get_buffer(avctx, ctx->current, AV_GET_BUFFER_FLAG_REF);
+        if (ret < 0)
+            return ret;
+
+        /* If malloc fails, reset len to avoid preserving an invalid value */
+        ctx->inflated_size = avctx->width * avctx->height * 3;
+        ret = av_reallocp(&ctx->inflated_buf, ctx->inflated_size);
+        if (ret < 0) {
+            ctx->inflated_size = 0;
+            return ret;
+        }
+    }
+
+    /* Inflate the frame after the 2 byte header */
+    ret = uncompress(ctx->inflated_buf, &ctx->inflated_size,
+                     avpkt->data + 2, avpkt->size - 2);
+    if (ret) {
+        av_log(avctx, AV_LOG_ERROR, "Deflate error %d.\n", ret);
+        return AVERROR_UNKNOWN;
+    }
+
+    /* When a keyframe is found, copy it (flipped) */
+    if (keyframe)
+        av_image_copy_plane(ctx->current->data[0] +
+                            ctx->current->linesize[0] * (avctx->height - 1),
+                            -1 * ctx->current->linesize[0],
+                            ctx->inflated_buf, avctx->width * 3,
+                            avctx->width * 3, avctx->height);
+    /* Otherwise sum the delta on top of the current frame */
+    else
+        sum_delta_flipped(ctx->current->data[0], ctx->current->linesize[0],
+                          ctx->inflated_buf, avctx->width * 3,
+                          avctx->width * 3, avctx->height);
+
+    /* Frame is ready to be output */
+    ret = av_frame_ref(frame, ctx->current);
+    if (ret < 0)
+        return ret;
+
+    /* Usual properties */
+    if (keyframe) {
+        frame->pict_type = AV_PICTURE_TYPE_I;
+        frame->key_frame = 1;
+    } else {
+        frame->pict_type = AV_PICTURE_TYPE_P;
+    }
+    *got_frame = 1;
+
+    return 0;
+}
+
+AVCodec ff_screenpresso_decoder = {
+    .name           = "screenpresso",
+    .long_name      = NULL_IF_CONFIG_SMALL("Screenpresso"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_SCREENPRESSO,
+    .init           = screenpresso_init,
+    .decode         = screenpresso_decode_frame,
+    .close          = screenpresso_close,
+    .priv_data_size = sizeof(ScreenpressoContext),
+    .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
+                      FF_CODEC_CAP_INIT_CLEANUP,
+};