9200514ad8
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.
203 lines
6.3 KiB
C
203 lines
6.3 KiB
C
/*
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* THP Demuxer
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* Copyright (c) 2007 Marco Gerards
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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 "libavutil/intreadwrite.h"
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#include "libavutil/intfloat.h"
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#include "avformat.h"
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#include "internal.h"
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typedef struct ThpDemuxContext {
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int version;
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int first_frame;
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int first_framesz;
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int last_frame;
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int compoff;
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int framecnt;
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AVRational fps;
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int frame;
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int next_frame;
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int next_framesz;
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int video_stream_index;
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int audio_stream_index;
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int compcount;
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unsigned char components[16];
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AVStream* vst;
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int has_audio;
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int audiosize;
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} ThpDemuxContext;
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static int thp_probe(AVProbeData *p)
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{
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/* check file header */
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if (AV_RL32(p->buf) == MKTAG('T', 'H', 'P', '\0'))
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return AVPROBE_SCORE_MAX;
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else
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return 0;
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}
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static int thp_read_header(AVFormatContext *s)
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{
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ThpDemuxContext *thp = s->priv_data;
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AVStream *st;
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AVIOContext *pb = s->pb;
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int i;
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/* Read the file header. */
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avio_rb32(pb); /* Skip Magic. */
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thp->version = avio_rb32(pb);
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avio_rb32(pb); /* Max buf size. */
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avio_rb32(pb); /* Max samples. */
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thp->fps = av_d2q(av_int2float(avio_rb32(pb)), INT_MAX);
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thp->framecnt = avio_rb32(pb);
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thp->first_framesz = avio_rb32(pb);
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avio_rb32(pb); /* Data size. */
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thp->compoff = avio_rb32(pb);
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avio_rb32(pb); /* offsetDataOffset. */
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thp->first_frame = avio_rb32(pb);
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thp->last_frame = avio_rb32(pb);
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thp->next_framesz = thp->first_framesz;
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thp->next_frame = thp->first_frame;
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/* Read the component structure. */
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avio_seek (pb, thp->compoff, SEEK_SET);
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thp->compcount = avio_rb32(pb);
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/* Read the list of component types. */
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avio_read(pb, thp->components, 16);
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for (i = 0; i < thp->compcount; i++) {
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if (thp->components[i] == 0) {
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if (thp->vst != 0)
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break;
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/* Video component. */
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st = avformat_new_stream(s, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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/* The denominator and numerator are switched because 1/fps
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is required. */
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avpriv_set_pts_info(st, 64, thp->fps.den, thp->fps.num);
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st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
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st->codecpar->codec_id = AV_CODEC_ID_THP;
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st->codecpar->codec_tag = 0; /* no fourcc */
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st->codecpar->width = avio_rb32(pb);
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st->codecpar->height = avio_rb32(pb);
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st->codecpar->sample_rate = av_q2d(thp->fps);
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thp->vst = st;
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thp->video_stream_index = st->index;
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if (thp->version == 0x11000)
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avio_rb32(pb); /* Unknown. */
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} else if (thp->components[i] == 1) {
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if (thp->has_audio != 0)
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break;
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/* Audio component. */
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st = avformat_new_stream(s, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
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st->codecpar->codec_id = AV_CODEC_ID_ADPCM_THP;
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st->codecpar->codec_tag = 0; /* no fourcc */
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st->codecpar->channels = avio_rb32(pb); /* numChannels. */
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st->codecpar->sample_rate = avio_rb32(pb); /* Frequency. */
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st->duration = avio_rb32(pb);
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avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
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thp->audio_stream_index = st->index;
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thp->has_audio = 1;
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}
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}
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return 0;
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}
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static int thp_read_packet(AVFormatContext *s,
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AVPacket *pkt)
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{
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ThpDemuxContext *thp = s->priv_data;
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AVIOContext *pb = s->pb;
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int size;
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int ret;
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if (thp->audiosize == 0) {
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/* Terminate when last frame is reached. */
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if (thp->frame >= thp->framecnt)
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return AVERROR(EIO);
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avio_seek(pb, thp->next_frame, SEEK_SET);
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/* Locate the next frame and read out its size. */
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thp->next_frame += thp->next_framesz;
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thp->next_framesz = avio_rb32(pb);
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avio_rb32(pb); /* Previous total size. */
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size = avio_rb32(pb); /* Total size of this frame. */
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/* Store the audiosize so the next time this function is called,
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the audio can be read. */
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if (thp->has_audio)
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thp->audiosize = avio_rb32(pb); /* Audio size. */
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else
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thp->frame++;
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ret = av_get_packet(pb, pkt, size);
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if (ret != size) {
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av_packet_unref(pkt);
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return AVERROR(EIO);
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}
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pkt->stream_index = thp->video_stream_index;
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} else {
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ret = av_get_packet(pb, pkt, thp->audiosize);
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if (ret != thp->audiosize) {
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av_packet_unref(pkt);
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return AVERROR(EIO);
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}
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pkt->stream_index = thp->audio_stream_index;
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if (thp->audiosize >= 8)
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pkt->duration = AV_RB32(&pkt->data[4]);
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thp->audiosize = 0;
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thp->frame++;
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}
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return 0;
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}
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AVInputFormat ff_thp_demuxer = {
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.name = "thp",
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.long_name = NULL_IF_CONFIG_SMALL("THP"),
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.priv_data_size = sizeof(ThpDemuxContext),
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.read_probe = thp_probe,
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.read_header = thp_read_header,
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.read_packet = thp_read_packet
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};
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