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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.
222 lines
6.7 KiB
C
222 lines
6.7 KiB
C
/*
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* WAV muxer
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* Copyright (c) 2001, 2002 Fabrice Bellard
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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 <stdint.h>
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#include <string.h>
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#include "libavutil/dict.h"
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#include "libavutil/common.h"
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#include "libavutil/mathematics.h"
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#include "libavutil/opt.h"
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#include "avformat.h"
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#include "avio.h"
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#include "avio_internal.h"
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#include "internal.h"
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#include "riff.h"
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typedef struct WAVMuxContext {
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const AVClass *class;
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int64_t data;
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int64_t fact_pos;
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int64_t minpts;
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int64_t maxpts;
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int last_duration;
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int write_bext;
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} WAVMuxContext;
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static inline void bwf_write_bext_string(AVFormatContext *s, const char *key, int maxlen)
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{
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AVDictionaryEntry *tag;
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int len = 0;
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if (tag = av_dict_get(s->metadata, key, NULL, 0)) {
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len = strlen(tag->value);
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len = FFMIN(len, maxlen);
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avio_write(s->pb, tag->value, len);
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}
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ffio_fill(s->pb, 0, maxlen - len);
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}
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static void bwf_write_bext_chunk(AVFormatContext *s)
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{
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AVDictionaryEntry *tmp_tag;
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uint64_t time_reference = 0;
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int64_t bext = ff_start_tag(s->pb, "bext");
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bwf_write_bext_string(s, "description", 256);
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bwf_write_bext_string(s, "originator", 32);
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bwf_write_bext_string(s, "originator_reference", 32);
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bwf_write_bext_string(s, "origination_date", 10);
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bwf_write_bext_string(s, "origination_time", 8);
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if (tmp_tag = av_dict_get(s->metadata, "time_reference", NULL, 0))
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time_reference = strtoll(tmp_tag->value, NULL, 10);
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avio_wl64(s->pb, time_reference);
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avio_wl16(s->pb, 1); // set version to 1
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if (tmp_tag = av_dict_get(s->metadata, "umid", NULL, 0)) {
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unsigned char umidpart_str[17] = {0};
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int i;
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uint64_t umidpart;
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int len = strlen(tmp_tag->value+2);
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for (i = 0; i < len/16; i++) {
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memcpy(umidpart_str, tmp_tag->value + 2 + (i*16), 16);
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umidpart = strtoll(umidpart_str, NULL, 16);
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avio_wb64(s->pb, umidpart);
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}
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ffio_fill(s->pb, 0, 64 - i*8);
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} else
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ffio_fill(s->pb, 0, 64); // zero UMID
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ffio_fill(s->pb, 0, 190); // Reserved
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if (tmp_tag = av_dict_get(s->metadata, "coding_history", NULL, 0))
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avio_put_str(s->pb, tmp_tag->value);
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ff_end_tag(s->pb, bext);
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}
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static int wav_write_header(AVFormatContext *s)
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{
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WAVMuxContext *wav = s->priv_data;
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AVIOContext *pb = s->pb;
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int64_t fmt;
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ffio_wfourcc(pb, "RIFF");
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avio_wl32(pb, 0); /* file length */
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ffio_wfourcc(pb, "WAVE");
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/* format header */
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fmt = ff_start_tag(pb, "fmt ");
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if (ff_put_wav_header(s, pb, s->streams[0]->codecpar) < 0) {
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const AVCodecDescriptor *desc = avcodec_descriptor_get(s->streams[0]->codecpar->codec_id);
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av_log(s, AV_LOG_ERROR, "%s codec not supported in WAVE format\n",
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desc ? desc->name : "unknown");
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return AVERROR(ENOSYS);
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}
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ff_end_tag(pb, fmt);
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if (s->streams[0]->codecpar->codec_tag != 0x01 /* hence for all other than PCM */
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&& s->pb->seekable) {
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wav->fact_pos = ff_start_tag(pb, "fact");
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avio_wl32(pb, 0);
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ff_end_tag(pb, wav->fact_pos);
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}
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if (wav->write_bext)
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bwf_write_bext_chunk(s);
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avpriv_set_pts_info(s->streams[0], 64, 1, s->streams[0]->codecpar->sample_rate);
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wav->maxpts = wav->last_duration = 0;
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wav->minpts = INT64_MAX;
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/* info header */
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ff_riff_write_info(s);
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/* data header */
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wav->data = ff_start_tag(pb, "data");
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avio_flush(pb);
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return 0;
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}
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static int wav_write_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AVIOContext *pb = s->pb;
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WAVMuxContext *wav = s->priv_data;
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avio_write(pb, pkt->data, pkt->size);
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if(pkt->pts != AV_NOPTS_VALUE) {
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wav->minpts = FFMIN(wav->minpts, pkt->pts);
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wav->maxpts = FFMAX(wav->maxpts, pkt->pts);
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wav->last_duration = pkt->duration;
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} else
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av_log(s, AV_LOG_ERROR, "wav_write_packet: NOPTS\n");
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return 0;
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}
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static int wav_write_trailer(AVFormatContext *s)
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{
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AVIOContext *pb = s->pb;
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WAVMuxContext *wav = s->priv_data;
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int64_t file_size;
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avio_flush(pb);
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if (s->pb->seekable) {
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ff_end_tag(pb, wav->data);
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/* update file size */
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file_size = avio_tell(pb);
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avio_seek(pb, 4, SEEK_SET);
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avio_wl32(pb, (uint32_t)(file_size - 8));
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avio_seek(pb, file_size, SEEK_SET);
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avio_flush(pb);
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if(s->streams[0]->codecpar->codec_tag != 0x01) {
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/* Update num_samps in fact chunk */
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int number_of_samples;
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number_of_samples = av_rescale(wav->maxpts - wav->minpts + wav->last_duration,
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s->streams[0]->codecpar->sample_rate * (int64_t)s->streams[0]->time_base.num,
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s->streams[0]->time_base.den);
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avio_seek(pb, wav->fact_pos, SEEK_SET);
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avio_wl32(pb, number_of_samples);
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avio_seek(pb, file_size, SEEK_SET);
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avio_flush(pb);
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}
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}
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return 0;
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}
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#define OFFSET(x) offsetof(WAVMuxContext, x)
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#define ENC AV_OPT_FLAG_ENCODING_PARAM
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static const AVOption options[] = {
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{ "write_bext", "Write BEXT chunk.", OFFSET(write_bext), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, ENC },
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{ NULL },
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};
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static const AVClass wav_muxer_class = {
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.class_name = "WAV muxer",
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.item_name = av_default_item_name,
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.option = options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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AVOutputFormat ff_wav_muxer = {
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.name = "wav",
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.long_name = NULL_IF_CONFIG_SMALL("WAV / WAVE (Waveform Audio)"),
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.mime_type = "audio/x-wav",
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.extensions = "wav",
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.priv_data_size = sizeof(WAVMuxContext),
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.audio_codec = AV_CODEC_ID_PCM_S16LE,
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.video_codec = AV_CODEC_ID_NONE,
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.write_header = wav_write_header,
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.write_packet = wav_write_packet,
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.write_trailer = wav_write_trailer,
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.flags = AVFMT_TS_NONSTRICT,
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.codec_tag = (const AVCodecTag* const []){ ff_codec_wav_tags, 0 },
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.priv_class = &wav_muxer_class,
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};
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