added first version of MPEG/DVB transport stream demux

Originally committed as revision 544 to svn://svn.ffmpeg.org/ffmpeg/trunk

libav/mpegts.c

+/*
+ * MPEG2 transport stream (aka DVB) demux
+ * Copyright (c) 2002 Gerard Lantau.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include "avformat.h"
+
+#define TS_FEC_PACKET_SIZE 204
+#define TS_PACKET_SIZE 188
+#define NB_PID_MAX 8192
+
+enum MpegTSState {
+    MPEGTS_HEADER = 0,
+    MPEGTS_PESHEADER_FILL,
+    MPEGTS_PESHEADER_FLAGS,
+    MPEGTS_PESHEADER_SIZE,
+    MPEGTS_PESHEADER_READ,
+    MPEGTS_PAYLOAD,
+    MPEGTS_SKIP,
+};
+
+/* enough for PES header + length */
+#define MAX_HEADER_SIZE 6
+
+typedef struct MpegTSStream {
+    int pid;
+    enum MpegTSState state;
+    int last_cc; /* last cc code (-1 if first packet) */
+    /* used to get the format */
+    int header_size;
+    int payload_size;
+    int pes_header_size;
+    AVStream *st;
+    unsigned char header[MAX_HEADER_SIZE];
+} MpegTSStream;
+
+typedef struct MpegTSContext {
+    int raw_packet_size; /* raw packet size, including FEC if present */
+    MpegTSStream *pids[NB_PID_MAX];
+} MpegTSContext;
+
+/* autodetect fec presence. Must have at least 1024 bytes  */
+static int get_packet_size(const unsigned char *buf, int size)
+{
+    int i;
+
+    if (size < (TS_FEC_PACKET_SIZE * 5 + 1))
+        return -1;
+    for(i=0;i<5;i++) {
+        if (buf[i * TS_PACKET_SIZE] != 0x47)
+            goto try_fec;
+    }
+    return TS_PACKET_SIZE;
+ try_fec:
+    for(i=0;i<5;i++) {
+        if (buf[i * TS_FEC_PACKET_SIZE] != 0x47)
+            return -1;
+    }
+    return TS_FEC_PACKET_SIZE;
+}
+
+static int mpegts_probe(AVProbeData *p)
+{
+    int size;
+    size = get_packet_size(p->buf, p->buf_size);
+    if (size < 0)
+        return 0;
+    return AVPROBE_SCORE_MAX;
+}
+
+static int mpegts_read_header(AVFormatContext *s,
+                              AVFormatParameters *ap)
+{
+    MpegTSContext *ts = s->priv_data;
+    ByteIOContext *pb = &s->pb;
+    unsigned char buf[1024];
+    int len;
+    INT64 pos;
+
+    /* read the first 1024 bytes to get packet size */
+    pos = url_ftell(pb);
+    len = get_buffer(pb, buf, sizeof(buf));
+    if (len != sizeof(buf))
+        goto fail;
+    ts->raw_packet_size = get_packet_size(buf, sizeof(buf));
+    if (ts->raw_packet_size <= 0)
+        goto fail;
+    /* go again to the start */
+    url_fseek(pb, pos, SEEK_SET);
+    return 0;
+ fail:
+    return -1;
+}
+
+/* return non zero if a packet could be constructed */
+static int mpegts_push_data(AVFormatContext *s, MpegTSStream *tss,
+                            AVPacket *pkt,
+                            const unsigned char *buf, int buf_size, int is_start)
+{
+    AVStream *st;
+    const unsigned char *p;
+    int len, code, codec_type, codec_id;
+
+    if (is_start) {
+        tss->state = MPEGTS_HEADER;
+        tss->header_size = 0;
+    }
+    p = buf;
+    while (buf_size > 0) {
+        len = buf_size;
+        switch(tss->state) {
+        case MPEGTS_HEADER:
+            if (len > MAX_HEADER_SIZE - tss->header_size)
+                len = MAX_HEADER_SIZE - tss->header_size;
+            memcpy(tss->header, p, len);
+            tss->header_size += len;
+            p += len;
+            buf_size -= len;
+            if (tss->header_size == MAX_HEADER_SIZE) {
+                /* we got all the PES or section header. We can now
+                   decide */
+#if 0
+                av_hex_dump(tss->header, tss->header_size);
+#endif
+                if (tss->header[0] == 0x00 && tss->header[1] == 0x00 &&
+                    tss->header[2] == 0x01) {
+                    /* it must be an mpeg2 PES stream */
+                    /* XXX: add AC3 support */
+                    code = tss->header[3] | 0x100;
+                    if (!((code >= 0x1c0 && code <= 0x1df) ||
+                          (code >= 0x1e0 && code <= 0x1ef)))
+                        goto skip;
+                    if (!tss->st) {
+                        /* allocate stream */
+                        if (code >= 0x1c0 && code <= 0x1df) {
+                            codec_type = CODEC_TYPE_AUDIO;
+                            codec_id = CODEC_ID_MP2;
+                        } else {
+                            codec_type = CODEC_TYPE_VIDEO;
+                            codec_id = CODEC_ID_MPEG1VIDEO;
+                        }
+                        st = av_new_stream(s, tss->pid);
+                        if (st) {
+                            st->priv_data = tss;
+                            st->codec.codec_type = codec_type;
+                            st->codec.codec_id = codec_id;
+                            tss->st = st;
+                        }
+                    }
+                    tss->state = MPEGTS_PESHEADER_FILL;
+                    tss->payload_size = (tss->header[4] << 8) | tss->header[5];
+                    if (tss->payload_size == 0)
+                        tss->payload_size = 65536;
+                } else {
+                    /* otherwise, it should be a table */
+                    /* skip packet */
+                skip:
+                    tss->state = MPEGTS_SKIP;
+                    continue;
+                }
+            }
+            break;
+            /**********************************************/
+            /* PES packing parsing */
+        case MPEGTS_PESHEADER_FILL:
+            /* skip filling */
+            code = *p++;
+            buf_size--;
+            tss->payload_size--;
+            if (code != 0xff) {
+                if ((code & 0xc0) != 0x80)
+                    goto skip;
+                tss->state = MPEGTS_PESHEADER_FLAGS;
+            }
+            break;
+        case MPEGTS_PESHEADER_FLAGS:
+            code = *p++;
+            buf_size--;
+            tss->payload_size--;
+            tss->state = MPEGTS_PESHEADER_SIZE;
+            break;
+        case MPEGTS_PESHEADER_SIZE:
+            tss->pes_header_size = *p++;
+            buf_size--;
+            tss->payload_size--;
+            tss->state = MPEGTS_PESHEADER_READ;
+            break;
+        case MPEGTS_PESHEADER_READ:
+            /* currently we do nothing except skipping */
+            if (len > tss->pes_header_size)
+                len = tss->pes_header_size;
+            p += len;
+            buf_size -= len;
+            tss->pes_header_size -= len;
+            tss->payload_size -= len;
+            if (tss->pes_header_size == 0)
+                tss->state = MPEGTS_PAYLOAD;
+            break;
+        case MPEGTS_PAYLOAD:
+            if (len > tss->payload_size)
+                len = tss->payload_size;
+            if (len > 0) {
+                if (tss->st && av_new_packet(pkt, buf_size) == 0) {
+                    memcpy(pkt->data, p, buf_size);
+                    pkt->stream_index = tss->st->index;
+                    return 1;
+                }
+                tss->payload_size -= len;
+            }
+            buf_size = 0;
+            break;
+        case MPEGTS_SKIP:
+            buf_size = 0;
+            break;
+        }
+    }
+    return 0;
+}
+
+static int mpegts_read_packet(AVFormatContext *s,
+                              AVPacket *pkt)
+{
+    MpegTSContext *ts = s->priv_data;
+    MpegTSStream *tss;
+    ByteIOContext *pb = &s->pb;
+    unsigned char packet[TS_FEC_PACKET_SIZE];
+    int len, pid, cc, cc_ok, afc;
+    const unsigned char *p;
+    
+    for(;;) {
+        len = get_buffer(pb, packet, ts->raw_packet_size);
+        if (len != ts->raw_packet_size)
+            return AVERROR_IO;
+        /* check paquet sync byte */
+        /* XXX: accept to resync ? */
+        if (packet[0] != 0x47)
+            return AVERROR_INVALIDDATA;
+        
+        pid = ((packet[1] & 0x1f) << 8) | packet[2];
+        tss = ts->pids[pid];
+        if (tss == NULL) {
+            /* if no pid found, then add a pid context */
+            tss = av_mallocz(sizeof(MpegTSStream));
+            if (!tss) 
+                continue;
+            ts->pids[pid] = tss;
+            tss->pid = pid;
+            tss->last_cc = -1;
+            //            printf("new pid=0x%x\n", pid);
+        }
+
+        /* continuity check (currently not used) */
+        cc = (packet[3] & 0xf);
+        cc_ok = (tss->last_cc < 0) || ((((tss->last_cc + 1) & 0x0f) == cc));
+        tss->last_cc = cc;
+        
+        /* skip adaptation field */
+        afc = (packet[3] >> 4) & 3;
+        p = packet + 4;
+        if (afc == 0) /* reserved value */
+            continue;
+        if (afc == 2) /* adaptation field only */
+            continue;
+        if (afc == 3) {
+            /* skip adapation field */
+            p += p[0] + 1;
+        }
+        /* if past the end of packet, ignore */
+        if (p >= packet + TS_PACKET_SIZE)
+            continue;
+    
+        if (mpegts_push_data(s, tss, pkt, p, TS_PACKET_SIZE - (p - packet), 
+                             packet[1] & 0x40))
+            break;
+    }
+    return 0;
+}
+
+static int mpegts_read_close(AVFormatContext *s)
+{
+    MpegTSContext *ts = s->priv_data;
+    int i;
+    for(i=0;i<NB_PID_MAX;i++)
+        av_freep(ts->pids[i]);
+    return 0;
+}
+
+AVInputFormat mpegts_demux = {
+    "mpegts",
+    "MPEG2 transport stream format",
+    sizeof(MpegTSContext),
+    mpegts_probe,
+    mpegts_read_header,
+    mpegts_read_packet,
+    mpegts_read_close,
+    flags: AVFMT_NOHEADER | AVFMT_SHOW_IDS,
+};
+
+int mpegts_init(void)
+{
+    av_register_input_format(&mpegts_demux);
+    return 0;
+}