[FFmpeg-devel] [PATCH] 8088flex TMV demuxer and decoder

Daniel Verkamp daniel
Thu Apr 23 19:19:16 CEST 2009


On Thu, Apr 23, 2009 at 12:07 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
[...]
>> +static int tmv_decode_frame(AVCodecContext *avctx, void *data,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ?int *data_size, AVPacket *avpkt)
>> +{
>> + ? ?TMVContext *tmv ? ?= avctx->priv_data;
>> + ? ?const uint8_t *src = avpkt->data;
>> + ? ?uint8_t *dst, *dst_char;
>> + ? ?unsigned char_cols = avctx->width >> 3;
>> + ? ?unsigned char_rows = avctx->height >> 3;
>> + ? ?unsigned x, y, mask, char_y, fg, bg, c;
>> +
>> + ? ?if (tmv->pic.data[0])
>> + ? ? ? ?avctx->release_buffer(avctx, &tmv->pic);
>> +
>> + ? ?if (avctx->get_buffer(avctx, &tmv->pic) < 0) {
>> + ? ? ? ?av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
>> + ? ? ? ?return -1;
>> + ? ?}
>> +
>> + ? ?tmv->pic.pict_type = FF_I_TYPE;
>> + ? ?tmv->pic.key_frame = 1;
>> + ? ?dst ? ? ? ? ? ? ? ?= tmv->pic.data[0];
>> +
>
>> + ? ?if (!tmv->pal_set) {
>> + ? ? ? ?tmv->pal_set ? ? ? ? ? ? ? ? = 1;
>> + ? ? ? ?tmv->pic.palette_has_changed = 1;
>> + ? ? ? ?memcpy(tmv->pic.data[1], ff_cga_palette, 16 * 4);
>> + ? ?}
>
> i dont think you can skip setting the palette like that
> Only if the buffer returned by (re)get_buffer() is identical to one where
> the palette has been set already (see AVFrame->age) could it be skiped
> and yes this likely is broken in existing codecs too
>

Is it acceptable to just set it every frame then, as in attached?
Also, is it acceptable to leave the unused part of the palette
(entries beyond 16) uninitialized?

Thanks,
-- Daniel Verkamp
-------------- next part --------------
>From 875219b6908ea4a6909860b6ecd1c4c7290ef4d7 Mon Sep 17 00:00:00 2001
From: Daniel Verkamp <daniel at drv.nu>
Date: Thu, 23 Apr 2009 10:31:10 -0500
Subject: [PATCH 2/2] 8088flex TMV video decoder

---
 libavcodec/Makefile    |    1 +
 libavcodec/allcodecs.c |    1 +
 libavcodec/avcodec.h   |    1 +
 libavcodec/tmv.c       |  102 ++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 105 insertions(+), 0 deletions(-)
 create mode 100644 libavcodec/tmv.c

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index b02b44e..e2f0b2c 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -221,6 +221,7 @@ OBJS-$(CONFIG_THP_DECODER)             += mjpegdec.o mjpeg.o
 OBJS-$(CONFIG_TIERTEXSEQVIDEO_DECODER) += tiertexseqv.o
 OBJS-$(CONFIG_TIFF_DECODER)            += tiff.o lzw.o faxcompr.o
 OBJS-$(CONFIG_TIFF_ENCODER)            += tiffenc.o rle.o lzwenc.o
+OBJS-$(CONFIG_TMV_DECODER)             += tmv.o cga_data.o
 OBJS-$(CONFIG_TRUEHD_DECODER)          += mlpdec.o mlp_parser.o mlp.o
 OBJS-$(CONFIG_TRUEMOTION1_DECODER)     += truemotion1.o
 OBJS-$(CONFIG_TRUEMOTION2_DECODER)     += truemotion2.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index bcc11d0..41cf661 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -162,6 +162,7 @@ void avcodec_register_all(void)
     REGISTER_DECODER (THP, thp);
     REGISTER_DECODER (TIERTEXSEQVIDEO, tiertexseqvideo);
     REGISTER_ENCDEC  (TIFF, tiff);
+    REGISTER_DECODER (TMV, tmv);
     REGISTER_DECODER (TRUEMOTION1, truemotion1);
     REGISTER_DECODER (TRUEMOTION2, truemotion2);
     REGISTER_DECODER (TSCC, tscc);
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 8016d82..7bea9ca 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -194,6 +194,7 @@ enum CodecID {
     CODEC_ID_AURA,
     CODEC_ID_AURA2,
     CODEC_ID_V210X,
+    CODEC_ID_TMV,
 
     /* various PCM "codecs" */
     CODEC_ID_PCM_S16LE= 0x10000,
diff --git a/libavcodec/tmv.c b/libavcodec/tmv.c
new file mode 100644
index 0000000..7bca086
--- /dev/null
+++ b/libavcodec/tmv.c
@@ -0,0 +1,102 @@
+/*
+ * 8088flex TMV video decoder
+ * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
+ *
+ * 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
+ */
+
+/**
+ * 8088flex TMV video decoder
+ * @file libavcodec/tmv.c
+ * @author Daniel Verkamp
+ * @sa http://www.oldskool.org/pc/8088_Corruption
+ */
+
+#include "avcodec.h"
+
+#include "cga_data.h"
+
+typedef struct TMVContext {
+    AVFrame pic;
+} TMVContext;
+
+static int tmv_decode_frame(AVCodecContext *avctx, void *data,
+                            int *data_size, AVPacket *avpkt)
+{
+    TMVContext *tmv    = avctx->priv_data;
+    const uint8_t *src = avpkt->data;
+    uint8_t *dst, *dst_char;
+    unsigned char_cols = avctx->width >> 3;
+    unsigned char_rows = avctx->height >> 3;
+    unsigned x, y, mask, char_y, fg, bg, c;
+
+    if (tmv->pic.data[0])
+        avctx->release_buffer(avctx, &tmv->pic);
+
+    if (avctx->get_buffer(avctx, &tmv->pic) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return -1;
+    }
+
+    tmv->pic.pict_type = FF_I_TYPE;
+    tmv->pic.key_frame = 1;
+    dst                = tmv->pic.data[0];
+
+    tmv->pic.palette_has_changed = 1;
+    memcpy(tmv->pic.data[1], ff_cga_palette, 16 * 4);
+
+    for (y = 0; y < char_rows; y++) {
+        for (x = 0; x < char_cols; x++) {
+            c  = *src++ * 8;
+            bg = *src  >> 4;
+            fg = *src++ & 0xF;
+
+            dst_char = dst + x * 8;
+            for (char_y = 0; char_y < 8; char_y++) {
+                for (mask = 0x80; mask; mask >>= 1) {
+                    *dst_char++ = ff_cga_font[c + char_y] & mask ? fg : bg;
+                }
+                dst_char += tmv->pic.linesize[0] - 8;
+            }
+        }
+        dst += tmv->pic.linesize[0] * 8;
+    }
+
+    *data_size = sizeof(AVFrame);
+    *(AVFrame *)data = tmv->pic;
+    return avpkt->size;
+}
+
+static av_cold int tmv_decode_close(AVCodecContext *avctx)
+{
+    TMVContext *tmv = avctx->priv_data;
+
+    if (tmv->pic.data[0])
+        avctx->release_buffer(avctx, &tmv->pic);
+
+    return 0;
+}
+
+AVCodec tmv_decoder = {
+    .name           = "tmv",
+    .type           = CODEC_TYPE_VIDEO,
+    .id             = CODEC_ID_TMV,
+    .priv_data_size = sizeof(TMVContext),
+    .close          = tmv_decode_close,
+    .decode         = tmv_decode_frame,
+    .long_name      = NULL_IF_CONFIG_SMALL("8088flex TMV"),
+};
-- 
1.6.2.3



More information about the ffmpeg-devel mailing list