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

Daniel Verkamp daniel
Wed May 6 16:43:35 CEST 2009


On Wed, May 6, 2009 at 7:34 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Wed, May 06, 2009 at 03:28:30AM -0500, Daniel Verkamp wrote:
[...]
>>
>> New demuxer patch attached, which now sets the bitrate for video
>> stream, resulting in correct automatic calculation of duration based
>> on file size.
>>
>> Anything else needed for the demuxer? ?CGA data and decoder are
>> already OK'd by Michael earlier in this thread.
> [...]
>> +typedef struct TMVContext {
>> + ? ?unsigned audio_chunk_size;
>
>> + ? ?unsigned comp_method;
>
> could be a local var, so could others
>

audio_chunk_size is needed in read_packet(); all other context vars
that can be local have now been made so.

Also added:
- a check to avoid dividing by zero when audio chunk size is 0
- video_chunk_size var to replace hardcoded 2000s everywhere

> [...]
> --
> Michael ? ? GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Thanks,
-- Daniel Verkamp
-------------- next part --------------
>From 50f0094cdb346c444b77b2a4c96fce249d88226b Mon Sep 17 00:00:00 2001
From: Daniel Verkamp <daniel at drv.nu>
Date: Fri, 24 Apr 2009 10:00:25 -0500
Subject: [PATCH 3/3] 8088flex TMV demuxer

---
 libavformat/Makefile     |    1 +
 libavformat/allformats.c |    1 +
 libavformat/tmv.c        |  156 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 158 insertions(+), 0 deletions(-)
 create mode 100644 libavformat/tmv.c

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 55717e6..b9e5eb7 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -210,6 +210,7 @@ OBJS-$(CONFIG_TG2_MUXER)                 += movenc.o riff.o isom.o avc.o
 OBJS-$(CONFIG_TGP_MUXER)                 += movenc.o riff.o isom.o avc.o
 OBJS-$(CONFIG_THP_DEMUXER)               += thp.o
 OBJS-$(CONFIG_TIERTEXSEQ_DEMUXER)        += tiertexseq.o
+OBJS-$(CONFIG_TMV_DEMUXER)               += tmv.o
 OBJS-$(CONFIG_TRUEHD_DEMUXER)            += raw.o id3v2.o
 OBJS-$(CONFIG_TRUEHD_MUXER)              += raw.o
 OBJS-$(CONFIG_TTA_DEMUXER)               += tta.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index e193af7..626b66c 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -182,6 +182,7 @@ void av_register_all(void)
     REGISTER_MUXER    (TGP, tgp);
     REGISTER_DEMUXER  (THP, thp);
     REGISTER_DEMUXER  (TIERTEXSEQ, tiertexseq);
+    REGISTER_DEMUXER  (TMV, tmv);
     REGISTER_MUXDEMUX (TRUEHD, truehd);
     REGISTER_DEMUXER  (TTA, tta);
     REGISTER_DEMUXER  (TXD, txd);
diff --git a/libavformat/tmv.c b/libavformat/tmv.c
new file mode 100644
index 0000000..a20e172
--- /dev/null
+++ b/libavformat/tmv.c
@@ -0,0 +1,156 @@
+/*
+ * 8088flex TMV file demuxer
+ * 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 file demuxer
+ * @file libavformat/tmv.c
+ * @author Daniel Verkamp
+ * @sa http://www.oldskool.org/pc/8088_Corruption
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avformat.h"
+
+enum {
+    TMV_PADDING = 0x01,
+    TMV_STEREO  = 0x02,
+};
+
+#define TMV_TAG MKTAG('T', 'M', 'A', 'V')
+
+typedef struct TMVContext {
+    unsigned audio_chunk_size;
+    unsigned video_chunk_size;
+    unsigned padding;
+    unsigned stream_index;
+} TMVContext;
+
+static int tmv_probe(AVProbeData *p)
+{
+    if (AV_RL32(p->buf) == TMV_TAG)
+        return AVPROBE_SCORE_MAX;
+    return 0;
+}
+
+static int tmv_read_header(AVFormatContext *s, AVFormatParameters *ap)
+{
+    TMVContext *tmv   = s->priv_data;
+    ByteIOContext *pb = s->pb;
+    AVStream *vst, *ast;
+    AVRational fps;
+    unsigned comp_method, char_cols, char_rows, features;
+
+    if (get_le32(pb) != TMV_TAG)
+        return -1;
+
+    if (!(vst = av_new_stream(s, 0)))
+        return AVERROR(ENOMEM);
+
+    if (!(ast = av_new_stream(s, 0)))
+        return AVERROR(ENOMEM);
+
+    ast->codec->sample_rate = get_le16(pb);
+    tmv->audio_chunk_size   = get_le16(pb);
+    if (!tmv->audio_chunk_size) {
+        av_log(s, AV_LOG_ERROR, "invalid audio chunk size\n");
+        return -1;
+    }
+
+    comp_method             = get_byte(pb);
+    if (comp_method) {
+        av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
+               comp_method);
+        return -1;
+    }
+
+    char_cols = get_byte(pb);
+    char_rows = get_byte(pb);
+    tmv->video_chunk_size = char_cols * char_rows * 2;
+
+    features  = get_byte(pb);
+    if (features & ~(TMV_PADDING | TMV_STEREO)) {
+        av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
+               features & ~(TMV_PADDING | TMV_STEREO));
+        return -1;
+    }
+
+    ast->codec->codec_type            = CODEC_TYPE_AUDIO;
+    ast->codec->codec_id              = CODEC_ID_PCM_U8;
+    ast->codec->sample_fmt            = SAMPLE_FMT_U8;
+    ast->codec->channels              = features & TMV_STEREO ? 2 : 1;
+    ast->codec->bits_per_coded_sample = 8;
+    ast->codec->bit_rate              = ast->codec->sample_rate *
+                                        ast->codec->bits_per_coded_sample;
+    av_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
+
+    fps.num = ast->codec->sample_rate * ast->codec->channels;
+    fps.den = tmv->audio_chunk_size;
+    av_reduce(&fps.num, &fps.den, fps.num, fps.den, 0xFFFFFFFFLL);
+
+    vst->codec->codec_type = CODEC_TYPE_VIDEO;
+    vst->codec->codec_id   = CODEC_ID_TMV;
+    vst->codec->pix_fmt    = PIX_FMT_PAL8;
+    vst->codec->width      = char_cols * 8;
+    vst->codec->height     = char_rows * 8;
+    av_set_pts_info(vst, 32, fps.den, fps.num);
+
+    if (features & TMV_PADDING)
+        tmv->padding =
+            ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) - 
+             (tmv->video_chunk_size + tmv->audio_chunk_size);
+
+    vst->codec->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
+                            fps.num * 8) / fps.den;
+
+    return 0;
+}
+
+static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    TMVContext *tmv   = s->priv_data;
+    ByteIOContext *pb = s->pb;
+    int ret, pkt_size = tmv->stream_index ?
+                        tmv->audio_chunk_size : tmv->video_chunk_size;
+
+    if (url_feof(pb))
+        return AVERROR_EOF;
+
+    ret = av_get_packet(pb, pkt, pkt_size);
+
+    if (tmv->stream_index)
+        url_fskip(pb, tmv->padding);
+
+    pkt->stream_index  = tmv->stream_index;
+    tmv->stream_index ^= 1;
+    pkt->flags        |= PKT_FLAG_KEY;
+
+    return ret;
+}
+
+AVInputFormat tmv_demuxer = {
+    "tmv",
+    NULL_IF_CONFIG_SMALL("8088flex TMV"),
+    sizeof(TMVContext),
+    tmv_probe,
+    tmv_read_header,
+    tmv_read_packet,
+    .flags = AVFMT_GENERIC_INDEX,
+};
-- 
1.6.2.3



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