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

[Michael Niedermayer]

On Wed, Apr 22, 2009 at 09:42:29AM -0500, Daniel Verkamp wrote:
> On Wed, Apr 22, 2009 at 12:46 AM, Diego Biurrun <diego at biurrun.de> wrote:
> > On Wed, Apr 22, 2009 at 12:37:14AM -0500, Daniel Verkamp wrote:
> >>
> >> This is a demuxer and decoder for the TMV file format from 8088flex,
> >> the updated version of the 8088 Corruption player. ?See
> >> http://www.oldskool.org/pc/8088_Corruption for samples.
> >>
> >> --- /dev/null
> >> +++ b/libavcodec/cga_data.h
> >
> > multiple inclusion guards
> >
> 
> Added.
> 
> >> --- /dev/null
> >> +++ b/libavcodec/tmv.c
> >> @@ -0,0 +1,116 @@
> >> + ? ?if (!tmv->pal_set) {
> >> + ? ? ? ?tmv->pal_set = 1;
> >> + ? ? ? ?tmv->pic.palette_has_changed = 1;
> >
> > align
> >
> 
> Fixed.
> 
> >> --- /dev/null
> >> +++ b/libavformat/tmv.c
> >> @@ -0,0 +1,149 @@
> >> + ? ?TMVContext *tmv = s->priv_data;
> >> + ? ?ByteIOContext *pb = s->pb;
> >
> > align
> >
> 
> Fixed.
> 
> >> + ? ? ? ?av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
> >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?tmv->comp_method);
> >
> > weird indentation
> >
> 
> Fixed in both places.
> 
> >> +static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
> >> +{
> >> + ? ?TMVContext *tmv = s->priv_data;
> >> + ? ?ByteIOContext *pb = s->pb;
> >
> > align
> >
> 
> Fixed.
> 
> > Diego
> 
> Also fixed calculation of padding in the demuxer (apparently none of
> the samples use that feature).
> 
> Thanks,
> -- Daniel Verkamp

> From 58d6d3a07f0a124ee84e792524aa1967325a3208 Mon Sep 17 00:00:00 2001
> From: Daniel Verkamp <daniel at drv.nu>
> Date: Wed, 22 Apr 2009 09:31:20 -0500
> Subject: [PATCH 1/3] CGA ROM font and palette

ok

[...]



> +    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;
> +            }
> +        }

compression wise this is not wise ...
you could store a bit for each of the 80x25 chars and only if its
1 store color+char oterwise copy from the same location of the previous frame
similarly the color could be reused from the last frame and just the char
updated

also if you sort the 256 chars based on their amount of foreground/background
pixels then chars might be nummerically correlated and compression of changed
chars might be possible by huffman coded differences.

speedwise it can of course be done faster by building more than 1 pixel at a
time but i guess theres no point, its better if it stays simple.


[...]
> +static int tmv_read_header(AVFormatContext *s, AVFormatParameters *ap)
> +{
> +    TMVContext *tmv   = s->priv_data;
> +    ByteIOContext *pb = s->pb;
> +    AVStream *vst, *ast;
> +
> +    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);
> +    tmv->comp_method        = get_byte(pb);
> +    if (tmv->comp_method) {
> +        av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
> +               tmv->comp_method);
> +        return -1;
> +    }
> +
> +    tmv->char_cols = get_byte(pb);
> +    tmv->char_rows = get_byte(pb);
> +
> +    tmv->features  = get_byte(pb);
> +    if (tmv->features & ~(TMV_PADDING | TMV_STEREO)) {
> +        av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
> +               tmv->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              = tmv->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;
> +    tmv->pts_inc[1]                   = tmv->audio_chunk_size;
> +    av_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
> +
> +    vst->codec->codec_type = CODEC_TYPE_VIDEO;
> +    vst->codec->codec_id   = CODEC_ID_TMV;
> +    vst->codec->pix_fmt    = PIX_FMT_PAL8;
> +    vst->codec->width      = tmv->char_cols * 8;
> +    vst->codec->height     = tmv->char_rows * 8;
> +    tmv->pts_inc[0]        = 1;
> +    av_set_pts_info(vst, 32, tmv->audio_chunk_size,
> +                             ast->codec->sample_rate * ast->codec->channels);

if you set av_set_pts_info() so each contain 1 frame then you should not
need to set pts of packets, lavf can add 1 as well

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

Concerning the gods, I have no means of knowing whether they exist or not
or of what sort they may be, because of the obscurity of the subject, and
the brevity of human life -- Protagoras
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