[FFmpeg-devel] [PATCH] Kega Game Video (KGV1) decoder
Daniel Verkamp
daniel
Thu Mar 4 00:23:32 CET 2010
On Tue, Mar 2, 2010 at 4:37 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Tue, Mar 02, 2010 at 11:46:38AM -0600, Daniel Verkamp wrote:
>> On Wed, Feb 3, 2010 at 9:02 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Wed, Feb 03, 2010 at 11:49:32AM -0600, Daniel Verkamp wrote:
>> >> On Wed, Feb 3, 2010 at 10:41 AM, Daniel Verkamp <daniel at drv.nu> wrote:
>> >> > Hi,
>> >> >
>> >> > This is a video capture codec used by the Kega emulator.
>> >> >
>> >> > See http://wiki.multimedia.cx/index.php?title=Kega_Video for more information.
>> >> >
>> >> > Thanks,
>> >> > -- Daniel Verkamp
>> >> >
[...]
>> +
>> +static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
>> +{
>> + ? ?const uint8_t *buf = avpkt->data;
>> + ? ?const uint8_t *buf_end = buf + avpkt->size;
>> + ? ?KgvContext * const c = avctx->priv_data;
>> + ? ?int offsets[7];
>> + ? ?uint16_t *out, *prev;
>> + ? ?int outcnt = 0, maxcnt;
>> + ? ?int w, h, i;
>> +
>> + ? ?if (avpkt->size < 2)
>> + ? ? ? ?return -1;
>> +
>> + ? ?w = (buf[0] + 1) * 8;
>> + ? ?h = (buf[1] + 1) * 8;
>> + ? ?buf += 2;
>> +
>> + ? ?if (avcodec_check_dimensions(avctx, w, h))
>> + ? ? ? ?return -1;
>> +
>> + ? ?if (w != avctx->width || h != avctx->height)
>> + ? ? ? ?avcodec_set_dimensions(avctx, w, h);
>> +
>> + ? ?maxcnt = w * h;
>> +
>
>> + ? ?c->pic.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE
>> + ? ? ? ? ? ? ? ? ? ? ? ?| FF_BUFFER_HINTS_REUSABLE;
>
> that should have no effect if you dont use *get_buffer()
>
Ok, removed.
>
>> +
>> + ? ?out = av_realloc(c->cur, w * h * 2);
>> + ? ?if (!out)
>> + ? ? ? ?return -1;
>> + ? ?c->cur = out;
>> +
>> + ? ?prev = av_realloc(c->prev, w * h * 2);
>> + ? ?if (!prev)
>> + ? ? ? ?return -1;
>> + ? ?c->prev = prev;
>> +
>> + ? ?for (i = 0; i < 7; i++)
>> + ? ? ? ?offsets[i] = -1;
>> +
>> + ? ?while (outcnt < maxcnt && buf_end - 2 > buf) {
>> + ? ? ? ?int code = AV_RL16(buf);
>> + ? ? ? ?buf += 2;
>> + ? ? ? ?if (!(code & 0x8000)) {
>> + ? ? ? ? ? ?out[outcnt++] = code; // rgb555 pixel coded directly
>> + ? ? ? ?} else {
>> + ? ? ? ? ? ?if ((code & 0x6000) == 0x6000) {
>> + ? ? ? ? ? ? ? ?// copy from previous frame
>> + ? ? ? ? ? ? ? ?int count = (code & 0x3FF) + 3;
>> + ? ? ? ? ? ? ? ?int oidx ?= (code >> ? 10) & 7;
>> + ? ? ? ? ? ? ? ?int start;
>> +
>> + ? ? ? ? ? ? ? ?if (offsets[oidx] == -1) {
>> + ? ? ? ? ? ? ? ? ? ?if (buf_end - 3 < buf)
>> + ? ? ? ? ? ? ? ? ? ? ? ?break;
>
>> + ? ? ? ? ? ? ? ? ? ?offsets[oidx] = AV_RL24(buf);
>> + ? ? ? ? ? ? ? ? ? ?if (offsets[oidx] < 0) {
>
> how can a 24bit number produce a negative int ?
>
Lack of thought on my part, removed.
>
>> + ? ? ? ? ? ? ? ? ? ? ? ?av_log(avctx, AV_LOG_ERROR, "negative offset\n");
>> + ? ? ? ? ? ? ? ? ? ? ? ?offsets[oidx] = 0;
>> + ? ? ? ? ? ? ? ? ? ? ? ?break;
>> + ? ? ? ? ? ? ? ? ? ?}
>> + ? ? ? ? ? ? ? ? ? ?buf += 3;
>> + ? ? ? ? ? ? ? ?}
>> +
>> + ? ? ? ? ? ? ? ?start = (outcnt + offsets[oidx]) % maxcnt;
>> +
>> + ? ? ? ? ? ? ? ?if (maxcnt - outcnt < count || maxcnt - start < count)
>> + ? ? ? ? ? ? ? ? ? ?break;
>> +
>> + ? ? ? ? ? ? ? ?for (i = 0; i < count; i++)
>> + ? ? ? ? ? ? ? ? ? ?out[outcnt++] = prev[start + i];
>> +
>> + ? ? ? ? ? ?} else {
>> + ? ? ? ? ? ? ? ?// copy from earlier in this frame
>> + ? ? ? ? ? ? ? ?int count;
>> + ? ? ? ? ? ? ? ?int offset = (code & 0x1FFF) + 1;
>> + ? ? ? ? ? ? ? ?uint16_t *inp;
>> + ? ? ? ? ? ? ? ?if (!(code & 0x6000)) {
>> + ? ? ? ? ? ? ? ? ? ?count = 2;
>> + ? ? ? ? ? ? ? ?} else if ((code & 0x6000) == 0x2000) {
>> + ? ? ? ? ? ? ? ? ? ?count = 3;
>> + ? ? ? ? ? ? ? ?} else {
>> + ? ? ? ? ? ? ? ? ? ?if (buf_end - 1 < buf)
>> + ? ? ? ? ? ? ? ? ? ? ? ?break;
>> + ? ? ? ? ? ? ? ? ? ?count = *buf++ + 4;
>> + ? ? ? ? ? ? ? ?}
>> +
>> + ? ? ? ? ? ? ? ?if (outcnt - offset < 0 || maxcnt - outcnt < count)
>> + ? ? ? ? ? ? ? ? ? ?break;
>> +
>> + ? ? ? ? ? ? ? ?inp = out + outcnt - offset;
>> + ? ? ? ? ? ? ? ?for (i = 0; i < count; i++)
>> + ? ? ? ? ? ? ? ? ? ?out[outcnt++] = inp[i];
>> + ? ? ? ? ? ?}
>
> these 2 look quite similar, i suspect they can be simplified by merging
> them
>
Copying loop and bounds check factored out.
Thanks,
-- Daniel Verkamp
-------------- next part --------------
>From c5154318cf7087606f69e1c1aaacc08d2fe47a49 Mon Sep 17 00:00:00 2001
From: Daniel Verkamp <daniel at drv.nu>
Date: Wed, 3 Feb 2010 11:22:03 -0500
Subject: [PATCH] Kega Game Video (KGV1) decoder
---
Changelog | 1 +
doc/general.texi | 2 +
libavcodec/Makefile | 1 +
libavcodec/allcodecs.c | 1 +
libavcodec/avcodec.h | 1 +
libavcodec/kgv1dec.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++++
libavformat/riff.c | 1 +
7 files changed, 185 insertions(+), 0 deletions(-)
create mode 100644 libavcodec/kgv1dec.c
diff --git a/Changelog b/Changelog
index cb276da..104651e 100644
--- a/Changelog
+++ b/Changelog
@@ -61,6 +61,7 @@ version <next>:
- FFprobe tool
- AMR-NB decoder
- RTSP muxer
+- Kega Game Video (KGV1) decoder
diff --git a/doc/general.texi b/doc/general.texi
index 6fed6c3..8f808e8 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -403,6 +403,8 @@ following image formats are supported:
@tab Used in Interplay .MVE files.
@item Karl Morton's video codec @tab @tab X
@tab Codec used in Worms games.
+ at item Kega Game Video (KGV1) @tab @tab X
+ @tab Kega emulator screen capture codec.
@item LCL (LossLess Codec Library) MSZH @tab @tab X
@item LCL (LossLess Codec Library) ZLIB @tab E @tab E
@item LOCO @tab @tab X
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index aed14ab..e37cf75 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -167,6 +167,7 @@ OBJS-$(CONFIG_INTERPLAY_VIDEO_DECODER) += interplayvideo.o
OBJS-$(CONFIG_JPEGLS_DECODER) += jpeglsdec.o jpegls.o \
mjpegdec.o mjpeg.o
OBJS-$(CONFIG_JPEGLS_ENCODER) += jpeglsenc.o jpegls.o
+OBJS-$(CONFIG_KGV1_DECODER) += kgv1dec.o
OBJS-$(CONFIG_KMVC_DECODER) += kmvc.o
OBJS-$(CONFIG_LJPEG_ENCODER) += ljpegenc.o mjpegenc.o mjpeg.o \
mpegvideo_enc.o motion_est.o \
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index f0a93a2..5dbf1dc 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -122,6 +122,7 @@ void avcodec_register_all(void)
REGISTER_DECODER (INDEO5, indeo5);
REGISTER_DECODER (INTERPLAY_VIDEO, interplay_video);
REGISTER_ENCDEC (JPEGLS, jpegls);
+ REGISTER_DECODER (KGV1, kgv1);
REGISTER_DECODER (KMVC, kmvc);
REGISTER_ENCODER (LJPEG, ljpeg);
REGISTER_DECODER (LOCO, loco);
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 31569d3..ea2a886 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -206,6 +206,7 @@ enum CodecID {
CODEC_ID_BINKVIDEO,
CODEC_ID_IFF_ILBM,
CODEC_ID_IFF_BYTERUN1,
+ CODEC_ID_KGV1,
/* various PCM "codecs" */
CODEC_ID_PCM_S16LE= 0x10000,
diff --git a/libavcodec/kgv1dec.c b/libavcodec/kgv1dec.c
new file mode 100644
index 0000000..c800bd4
--- /dev/null
+++ b/libavcodec/kgv1dec.c
@@ -0,0 +1,178 @@
+/*
+ * Kega Game Video (KGV1) decoder
+ * Copyright (c) 2010 Daniel Verkamp
+ *
+ * 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
+ */
+
+/**
+ * @file libavcodec/kgv1dec.c
+ * Kega Game Video decoder
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avcodec.h"
+
+typedef struct {
+ AVCodecContext *avctx;
+ AVFrame pic;
+ uint16_t *prev, *cur;
+} KgvContext;
+
+static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
+{
+ const uint8_t *buf = avpkt->data;
+ const uint8_t *buf_end = buf + avpkt->size;
+ KgvContext * const c = avctx->priv_data;
+ int offsets[7];
+ uint16_t *out, *prev;
+ int outcnt = 0, maxcnt;
+ int w, h, i;
+
+ if (avpkt->size < 2)
+ return -1;
+
+ w = (buf[0] + 1) * 8;
+ h = (buf[1] + 1) * 8;
+ buf += 2;
+
+ if (avcodec_check_dimensions(avctx, w, h))
+ return -1;
+
+ if (w != avctx->width || h != avctx->height)
+ avcodec_set_dimensions(avctx, w, h);
+
+ maxcnt = w * h;
+
+ c->pic.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE
+ | FF_BUFFER_HINTS_REUSABLE;
+
+ out = av_realloc(c->cur, w * h * 2);
+ if (!out)
+ return -1;
+ c->cur = out;
+
+ prev = av_realloc(c->prev, w * h * 2);
+ if (!prev)
+ return -1;
+ c->prev = prev;
+
+ for (i = 0; i < 7; i++)
+ offsets[i] = -1;
+
+ while (outcnt < maxcnt && buf_end - 2 > buf) {
+ int code = AV_RL16(buf);
+ buf += 2;
+ if (!(code & 0x8000)) {
+ out[outcnt++] = code; // rgb555 pixel coded directly
+ } else {
+ if ((code & 0x6000) == 0x6000) {
+ // copy from previous frame
+ int count = (code & 0x3FF) + 3;
+ int oidx = (code >> 10) & 7;
+ int start;
+
+ if (offsets[oidx] == -1) {
+ if (buf_end - 3 < buf)
+ break;
+ offsets[oidx] = AV_RL24(buf);
+ if (offsets[oidx] < 0) {
+ av_log(avctx, AV_LOG_ERROR, "negative offset\n");
+ offsets[oidx] = 0;
+ break;
+ }
+ buf += 3;
+ }
+
+ start = (outcnt + offsets[oidx]) % maxcnt;
+
+ if (maxcnt - outcnt < count || maxcnt - start < count)
+ break;
+
+ for (i = 0; i < count; i++)
+ out[outcnt++] = prev[start + i];
+
+ } else {
+ // copy from earlier in this frame
+ int count;
+ int offset = (code & 0x1FFF) + 1;
+ uint16_t *inp;
+ if (!(code & 0x6000)) {
+ count = 2;
+ } else if ((code & 0x6000) == 0x2000) {
+ count = 3;
+ } else {
+ if (buf_end - 1 < buf)
+ break;
+ count = *buf++ + 4;
+ }
+
+ if (outcnt - offset < 0 || maxcnt - outcnt < count)
+ break;
+
+ inp = out + outcnt - offset;
+ for (i = 0; i < count; i++)
+ out[outcnt++] = inp[i];
+ }
+ }
+ }
+
+ if (outcnt - maxcnt)
+ av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
+
+ c->pic.data[0] = (uint8_t *)c->cur;
+ c->pic.linesize[0] = w * 2;
+
+ *data_size = sizeof(AVFrame);
+ *(AVFrame*)data = c->pic;
+
+ FFSWAP(uint16_t *, c->cur, c->prev);
+
+ return avpkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+ KgvContext * const c = avctx->priv_data;
+
+ c->avctx = avctx;
+ avctx->pix_fmt = PIX_FMT_RGB555;
+
+ return 0;
+}
+
+static av_cold int decode_end(AVCodecContext *avctx)
+{
+ KgvContext * const c = avctx->priv_data;
+
+ av_freep(&c->cur);
+ av_freep(&c->prev);
+
+ return 0;
+}
+
+AVCodec kgv1_decoder = {
+ "kgv1",
+ CODEC_TYPE_VIDEO,
+ CODEC_ID_KGV1,
+ sizeof(KgvContext),
+ decode_init,
+ NULL,
+ decode_end,
+ decode_frame,
+ .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
+};
diff --git a/libavformat/riff.c b/libavformat/riff.c
index 0a3bc95..f241421 100644
--- a/libavformat/riff.c
+++ b/libavformat/riff.c
@@ -240,6 +240,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
{ CODEC_ID_AURA, MKTAG('A', 'U', 'R', 'A') },
{ CODEC_ID_AURA2, MKTAG('A', 'U', 'R', '2') },
{ CODEC_ID_DPX, MKTAG('d', 'p', 'x', ' ') },
+ { CODEC_ID_KGV1, MKTAG('K', 'G', 'V', '1') },
{ CODEC_ID_NONE, 0 }
};
--
1.6.6.1
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