176 lines
6.4 KiB
C
176 lines
6.4 KiB
C
/*
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* a64 muxer
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* Copyright (c) 2009 Tobias Bindhammer
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavcodec/avcodec.h"
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#include "libavcodec/a64enc.h"
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#include "libavcodec/bytestream.h"
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#include "avformat.h"
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typedef struct A64MuxerContext {
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int interleaved;
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AVPacket prev_pkt;
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int prev_frame_count;
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} A64MuxerContext;
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static int a64_write_header(struct AVFormatContext *s)
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{
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AVCodecContext *avctx = s->streams[0]->codec;
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A64MuxerContext *c = s->priv_data;
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uint8_t header[5] = {
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0x00, //load
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0x40, //address
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0x00, //mode
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0x00, //charset_lifetime (multi only)
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0x00 //fps in 50/fps;
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};
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c->interleaved = 0;
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switch (avctx->codec->id) {
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case AV_CODEC_ID_A64_MULTI:
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header[2] = 0x00;
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header[3] = AV_RB32(avctx->extradata+0);
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header[4] = 2;
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break;
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case AV_CODEC_ID_A64_MULTI5:
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header[2] = 0x01;
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header[3] = AV_RB32(avctx->extradata+0);
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header[4] = 3;
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break;
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default:
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return AVERROR(EINVAL);
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}
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avio_write(s->pb, header, 2);
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c->prev_pkt.size = 0;
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c->prev_frame_count = 0;
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return 0;
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}
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static int a64_write_packet(struct AVFormatContext *s, AVPacket *pkt)
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{
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AVCodecContext *avctx = s->streams[0]->codec;
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A64MuxerContext *c = s->priv_data;
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int i, j;
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int ch_chunksize;
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int lifetime;
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int frame_count;
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int charset_size;
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int frame_size;
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int num_frames;
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/* fetch values from extradata */
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switch (avctx->codec->id) {
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case AV_CODEC_ID_A64_MULTI:
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case AV_CODEC_ID_A64_MULTI5:
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if(c->interleaved) {
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/* Write interleaved, means we insert chunks of the future charset before each current frame.
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* Reason: if we load 1 charset + corresponding frames in one block on c64, we need to store
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* them first and then display frame by frame to keep in sync. Thus we would read and write
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* the data for colram from/to ram first and waste too much time. If we interleave and send the
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* charset beforehand, we assemble a new charset chunk by chunk, write current screen data to
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* screen-ram to be displayed and decode the colram directly to colram-location $d800 during
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* the overscan, while reading directly from source.
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* This is the only way so far, to achieve 25fps on c64 */
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if(avctx->extradata) {
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/* fetch values from extradata */
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lifetime = AV_RB32(avctx->extradata + 0);
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frame_count = AV_RB32(avctx->extradata + 4);
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charset_size = AV_RB32(avctx->extradata + 8);
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frame_size = AV_RB32(avctx->extradata + 12);
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/* TODO: sanity checks? */
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} else {
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av_log(avctx, AV_LOG_ERROR, "extradata not set\n");
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return AVERROR(EINVAL);
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}
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ch_chunksize=charset_size/lifetime;
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/* TODO: check if charset/size is % lifetime, but maybe check in codec */
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if(pkt->data) num_frames = lifetime;
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else num_frames = c->prev_frame_count;
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for(i = 0; i < num_frames; i++) {
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if(pkt->data) {
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/* if available, put newest charset chunk into buffer */
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avio_write(s->pb, pkt->data + ch_chunksize * i, ch_chunksize);
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} else {
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/* a bit ugly, but is there an alternative to put many zeros? */
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for(j = 0; j < ch_chunksize; j++) avio_w8(s->pb, 0);
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}
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if(c->prev_pkt.data) {
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/* put frame (screen + colram) from last packet into buffer */
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avio_write(s->pb, c->prev_pkt.data + charset_size + frame_size * i, frame_size);
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} else {
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/* a bit ugly, but is there an alternative to put many zeros? */
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for(j = 0; j < frame_size; j++) avio_w8(s->pb, 0);
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}
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}
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/* backup current packet for next turn */
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if(pkt->data) {
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/* no backup packet yet? create one! */
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if(!c->prev_pkt.data) av_new_packet(&c->prev_pkt, pkt->size);
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/* we have a packet and data is big enough, reuse it */
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if(c->prev_pkt.data && c->prev_pkt.size >= pkt->size) {
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memcpy(c->prev_pkt.data, pkt->data, pkt->size);
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c->prev_pkt.size = pkt->size;
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} else {
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av_log(avctx, AV_LOG_ERROR, "Too less memory for prev_pkt.\n");
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return AVERROR(ENOMEM);
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}
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}
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c->prev_frame_count = frame_count;
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break;
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}
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default:
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/* Write things as is. Nice for self-contained frames from non-multicolor modes or if played
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* directly from ram and not from a streaming device (rrnet/mmc) */
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if(pkt) avio_write(s->pb, pkt->data, pkt->size);
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break;
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}
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avio_flush(s->pb);
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return 0;
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}
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static int a64_write_trailer(struct AVFormatContext *s)
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{
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A64MuxerContext *c = s->priv_data;
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AVPacket pkt = {0};
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/* need to flush last packet? */
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if(c->interleaved) a64_write_packet(s, &pkt);
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/* discard backed up packet */
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if(c->prev_pkt.data) av_destruct_packet(&c->prev_pkt);
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return 0;
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}
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AVOutputFormat ff_a64_muxer = {
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.name = "a64",
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.long_name = NULL_IF_CONFIG_SMALL("a64 - video for Commodore 64"),
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.extensions = "a64, A64",
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.priv_data_size = sizeof (A64Context),
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.video_codec = AV_CODEC_ID_A64_MULTI,
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.write_header = a64_write_header,
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.write_packet = a64_write_packet,
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.write_trailer = a64_write_trailer,
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};
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