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/*
* a64 muxer
* Copyright (c) 2009 Tobias Bindhammer
*
* 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
*/
#include "libavcodec/avcodec.h"
#include "libavcodec/a64enc.h"
#include "libavcodec/bytestream.h"
#include "avformat.h"
typedef struct A64MuxerContext {
int interleaved;
AVPacket prev_pkt;
int prev_frame_count;
} A64MuxerContext;
static int a64_write_header(struct AVFormatContext *s)
{
AVCodecContext *avctx = s->streams[0]->codec;
A64MuxerContext *c = s->priv_data;
uint8_t header[5] = {
0x00, //load
0x40, //address
0x00, //mode
0x00, //charset_lifetime (multi only)
0x00 //fps in 50/fps;
};
c->interleaved = 0;
switch (avctx->codec->id) {
case AV_CODEC_ID_A64_MULTI:
header[2] = 0x00;
header[3] = AV_RB32(avctx->extradata+0);
header[4] = 2;
break;
case AV_CODEC_ID_A64_MULTI5:
header[2] = 0x01;
header[3] = AV_RB32(avctx->extradata+0);
header[4] = 3;
break;
default:
return AVERROR(EINVAL);
}
avio_write(s->pb, header, 2);
c->prev_pkt.size = 0;
c->prev_frame_count = 0;
return 0;
}
static int a64_write_packet(struct AVFormatContext *s, AVPacket *pkt)
{
AVCodecContext *avctx = s->streams[0]->codec;
A64MuxerContext *c = s->priv_data;
int i, j;
int ch_chunksize;
int lifetime;
int frame_count;
int charset_size;
int frame_size;
int num_frames;
/* fetch values from extradata */
switch (avctx->codec->id) {
case AV_CODEC_ID_A64_MULTI:
case AV_CODEC_ID_A64_MULTI5:
if(c->interleaved) {
/* Write interleaved, means we insert chunks of the future charset before each current frame.
* Reason: if we load 1 charset + corresponding frames in one block on c64, we need to store
* them first and then display frame by frame to keep in sync. Thus we would read and write
* the data for colram from/to ram first and waste too much time. If we interleave and send the
* charset beforehand, we assemble a new charset chunk by chunk, write current screen data to
* screen-ram to be displayed and decode the colram directly to colram-location $d800 during
* the overscan, while reading directly from source.
* This is the only way so far, to achieve 25fps on c64 */
if(avctx->extradata) {
/* fetch values from extradata */
lifetime = AV_RB32(avctx->extradata + 0);
frame_count = AV_RB32(avctx->extradata + 4);
charset_size = AV_RB32(avctx->extradata + 8);
frame_size = AV_RB32(avctx->extradata + 12);
/* TODO: sanity checks? */
} else {
av_log(avctx, AV_LOG_ERROR, "extradata not set\n");
return AVERROR(EINVAL);
}
ch_chunksize=charset_size/lifetime;
/* TODO: check if charset/size is % lifetime, but maybe check in codec */
if(pkt->data) num_frames = lifetime;
else num_frames = c->prev_frame_count;
for(i = 0; i < num_frames; i++) {
if(pkt->data) {
/* if available, put newest charset chunk into buffer */
avio_write(s->pb, pkt->data + ch_chunksize * i, ch_chunksize);
} else {
/* a bit ugly, but is there an alternative to put many zeros? */
for(j = 0; j < ch_chunksize; j++) avio_w8(s->pb, 0);
}
if(c->prev_pkt.data) {
/* put frame (screen + colram) from last packet into buffer */
avio_write(s->pb, c->prev_pkt.data + charset_size + frame_size * i, frame_size);
} else {
/* a bit ugly, but is there an alternative to put many zeros? */
for(j = 0; j < frame_size; j++) avio_w8(s->pb, 0);
}
}
/* backup current packet for next turn */
if(pkt->data) {
/* no backup packet yet? create one! */
if(!c->prev_pkt.data) av_new_packet(&c->prev_pkt, pkt->size);
/* we have a packet and data is big enough, reuse it */
if(c->prev_pkt.data && c->prev_pkt.size >= pkt->size) {
memcpy(c->prev_pkt.data, pkt->data, pkt->size);
c->prev_pkt.size = pkt->size;
} else {
av_log(avctx, AV_LOG_ERROR, "Too less memory for prev_pkt.\n");
return AVERROR(ENOMEM);
}
}
c->prev_frame_count = frame_count;
break;
}
default:
/* Write things as is. Nice for self-contained frames from non-multicolor modes or if played
* directly from ram and not from a streaming device (rrnet/mmc) */
if(pkt) avio_write(s->pb, pkt->data, pkt->size);
break;
}
avio_flush(s->pb);
return 0;
}
static int a64_write_trailer(struct AVFormatContext *s)
{
A64MuxerContext *c = s->priv_data;
AVPacket pkt = {0};
/* need to flush last packet? */
if(c->interleaved) a64_write_packet(s, &pkt);
/* discard backed up packet */
if(c->prev_pkt.data) av_destruct_packet(&c->prev_pkt);
return 0;
}
AVOutputFormat ff_a64_muxer = {
.name = "a64",
.long_name = NULL_IF_CONFIG_SMALL("a64 - video for Commodore 64"),
.extensions = "a64, A64",
.priv_data_size = sizeof (A64Context),
.video_codec = AV_CODEC_ID_A64_MULTI,
.write_header = a64_write_header,
.write_packet = a64_write_packet,
.write_trailer = a64_write_trailer,
};
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