FFmpeg/libavformat/yop.c
Anton Khirnov 9200514ad8 lavf: replace AVStream.codec with AVStream.codecpar
Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.

In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.

There are multiple important problems with this approach:
    - the fields in AVCodecContext are in general one of
        * stream parameters
        * codec options
        * codec state
      However, it's not clear which ones are which. It is consequently
      unclear which fields are a demuxer allowed to set or a muxer allowed to
      read. This leads to erratic behaviour depending on whether decoding or
      encoding is being performed or not (and whether it uses the AVStream
      embedded codec context).
    - various synchronization issues arising from the fact that the same
      context is used by several different APIs (muxers/demuxers,
      parsers, bitstream filters and encoders/decoders) simultaneously, with
      there being no clear rules for who can modify what and the different
      processes being typically delayed with respect to each other.
    - avformat_find_stream_info() making it necessary to support opening
      and closing a single codec context multiple times, thus
      complicating the semantics of freeing various allocated objects in the
      codec context.

Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
2016-02-23 17:01:58 +01:00

221 lines
6.5 KiB
C

/*
* Psygnosis YOP demuxer
*
* Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
* derived from the code by
* Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
*
* 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 "libavutil/channel_layout.h"
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "internal.h"
typedef struct yop_dec_context {
AVPacket video_packet;
int odd_frame;
int frame_size;
int audio_block_length;
int palette_size;
} YopDecContext;
static int yop_probe(AVProbeData *probe_packet)
{
if (AV_RB16(probe_packet->buf) == AV_RB16("YO") &&
probe_packet->buf[6] &&
probe_packet->buf[7] &&
!(probe_packet->buf[8] & 1) &&
!(probe_packet->buf[10] & 1))
return AVPROBE_SCORE_MAX * 3 / 4;
return 0;
}
static int yop_read_header(AVFormatContext *s)
{
YopDecContext *yop = s->priv_data;
AVIOContext *pb = s->pb;
AVCodecParameters *audio_par, *video_par;
AVStream *audio_stream, *video_stream;
int frame_rate, ret;
audio_stream = avformat_new_stream(s, NULL);
video_stream = avformat_new_stream(s, NULL);
// Extra data that will be passed to the decoder
video_stream->codecpar->extradata = av_mallocz(8 + AV_INPUT_BUFFER_PADDING_SIZE);
if (!video_stream->codecpar->extradata)
return AVERROR(ENOMEM);
video_stream->codecpar->extradata_size = 8;
// Audio
audio_par = audio_stream->codecpar;
audio_par->codec_type = AVMEDIA_TYPE_AUDIO;
audio_par->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;
audio_par->channels = 1;
audio_par->channel_layout = AV_CH_LAYOUT_MONO;
audio_par->sample_rate = 22050;
// Video
video_par = video_stream->codecpar;
video_par->codec_type = AVMEDIA_TYPE_VIDEO;
video_par->codec_id = AV_CODEC_ID_YOP;
avio_skip(pb, 6);
frame_rate = avio_r8(pb);
yop->frame_size = avio_r8(pb) * 2048;
video_par->width = avio_rl16(pb);
video_par->height = avio_rl16(pb);
video_stream->sample_aspect_ratio = (AVRational){1, 2};
ret = avio_read(pb, video_par->extradata, 8);
if (ret < 8)
return ret < 0 ? ret : AVERROR_EOF;
yop->palette_size = video_par->extradata[0] * 3 + 4;
yop->audio_block_length = AV_RL16(video_par->extradata + 6);
// 1840 samples per frame, 1 nibble per sample; hence 1840/2 = 920
if (yop->audio_block_length < 920 ||
yop->audio_block_length + yop->palette_size >= yop->frame_size) {
av_log(s, AV_LOG_ERROR, "YOP has invalid header\n");
return AVERROR_INVALIDDATA;
}
avio_seek(pb, 2048, SEEK_SET);
avpriv_set_pts_info(video_stream, 32, 1, frame_rate);
return 0;
}
static int yop_read_packet(AVFormatContext *s, AVPacket *pkt)
{
YopDecContext *yop = s->priv_data;
AVIOContext *pb = s->pb;
int ret;
int actual_video_data_size = yop->frame_size -
yop->audio_block_length - yop->palette_size;
yop->video_packet.stream_index = 1;
if (yop->video_packet.data) {
*pkt = yop->video_packet;
yop->video_packet.data = NULL;
yop->video_packet.buf = NULL;
yop->video_packet.size = 0;
pkt->data[0] = yop->odd_frame;
pkt->flags |= AV_PKT_FLAG_KEY;
yop->odd_frame ^= 1;
return pkt->size;
}
ret = av_new_packet(&yop->video_packet,
yop->frame_size - yop->audio_block_length);
if (ret < 0)
return ret;
yop->video_packet.pos = avio_tell(pb);
ret = avio_read(pb, yop->video_packet.data, yop->palette_size);
if (ret < 0) {
goto err_out;
}else if (ret < yop->palette_size) {
ret = AVERROR_EOF;
goto err_out;
}
ret = av_get_packet(pb, pkt, 920);
if (ret < 0)
goto err_out;
// Set position to the start of the frame
pkt->pos = yop->video_packet.pos;
avio_skip(pb, yop->audio_block_length - ret);
ret = avio_read(pb, yop->video_packet.data + yop->palette_size,
actual_video_data_size);
if (ret < 0)
goto err_out;
else if (ret < actual_video_data_size)
av_shrink_packet(&yop->video_packet, yop->palette_size + ret);
// Arbitrarily return the audio data first
return yop->audio_block_length;
err_out:
av_packet_unref(&yop->video_packet);
return ret;
}
static int yop_read_close(AVFormatContext *s)
{
YopDecContext *yop = s->priv_data;
av_packet_unref(&yop->video_packet);
return 0;
}
static int yop_read_seek(AVFormatContext *s, int stream_index,
int64_t timestamp, int flags)
{
YopDecContext *yop = s->priv_data;
int64_t frame_pos, pos_min, pos_max;
int frame_count;
if (!stream_index)
return -1;
pos_min = s->internal->data_offset;
pos_max = avio_size(s->pb) - yop->frame_size;
frame_count = (pos_max - pos_min) / yop->frame_size;
timestamp = FFMAX(0, FFMIN(frame_count, timestamp));
frame_pos = timestamp * yop->frame_size + pos_min;
if (avio_seek(s->pb, frame_pos, SEEK_SET) < 0)
return -1;
av_packet_unref(&yop->video_packet);
yop->odd_frame = timestamp & 1;
return 0;
}
AVInputFormat ff_yop_demuxer = {
.name = "yop",
.long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP"),
.priv_data_size = sizeof(YopDecContext),
.read_probe = yop_probe,
.read_header = yop_read_header,
.read_packet = yop_read_packet,
.read_close = yop_read_close,
.read_seek = yop_read_seek,
.extensions = "yop",
.flags = AVFMT_GENERIC_INDEX,
};