avformat: add TiVo ty demuxer

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 765 insertions, 0 deletions

diff --git a/libavformat/ty.c b/libavformat/ty.c
new file mode 100644
index 0000000000..bd871cba2e
--- /dev/null
+++ b/libavformat/ty.c
@@ -0,0 +1,765 @@
+/*
+ * TiVo ty stream demuxer
+ * Copyright (c) 2005 VLC authors and VideoLAN
+ * Copyright (c) 2005 by Neal Symms (tivo@freakinzoo.com) - February 2005
+ * based on code by Christopher Wingert for tivo-mplayer
+ * tivo(at)wingert.org, February 2003
+ * Copyright (c) 2017 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avformat.h"
+#include "internal.h"
+#include "mpeg.h"
+
+#define SERIES1_PES_LENGTH  11    /* length of audio PES hdr on S1 */
+#define SERIES2_PES_LENGTH  16    /* length of audio PES hdr on S2 */
+#define AC3_PES_LENGTH      14    /* length of audio PES hdr for AC3 */
+#define VIDEO_PES_LENGTH    16    /* length of video PES header */
+#define DTIVO_PTS_OFFSET    6     /* offs into PES for MPEG PTS on DTivo */
+#define SA_PTS_OFFSET       9     /* offset into PES for MPEG PTS on SA */
+#define AC3_PTS_OFFSET      9     /* offset into PES for AC3 PTS on DTivo */
+#define VIDEO_PTS_OFFSET    9     /* offset into PES for video PTS on all */
+#define AC3_PKT_LENGTH      1536  /* size of TiVo AC3 pkts (w/o PES hdr) */
+
+static const uint8_t ty_VideoPacket[]     = { 0x00, 0x00, 0x01, 0xe0 };
+static const uint8_t ty_MPEGAudioPacket[] = { 0x00, 0x00, 0x01, 0xc0 };
+static const uint8_t ty_AC3AudioPacket[]  = { 0x00, 0x00, 0x01, 0xbd };
+
+#define TIVO_PES_FILEID   0xf5467abd
+#define CHUNK_SIZE        (128 * 1024)
+#define CHUNK_PEEK_COUNT  3      /* number of chunks to probe */
+
+typedef struct TyRecHdr {
+    int64_t   rec_size;
+    uint8_t   ex[2];
+    uint8_t   rec_type;
+    uint8_t   subrec_type;
+    uint64_t  ty_pts;            /* TY PTS in the record header */
+} TyRecHdr;
+
+typedef enum {
+    TIVO_TYPE_UNKNOWN,
+    TIVO_TYPE_SA,
+    TIVO_TYPE_DTIVO
+} TiVo_type;
+
+typedef enum {
+    TIVO_SERIES_UNKNOWN,
+    TIVO_SERIES1,
+    TIVO_SERIES2
+} TiVo_series;
+
+typedef enum {
+    TIVO_AUDIO_UNKNOWN,
+    TIVO_AUDIO_AC3,
+    TIVO_AUDIO_MPEG
+} TiVo_audio;
+
+typedef struct TySeqTable {
+    uint64_t    timestamp;
+    uint8_t     chunk_bitmask[8];
+} TySeqTable;
+
+typedef struct TYDemuxContext {
+    unsigned        cur_chunk;
+    unsigned        cur_chunk_pos;
+    int64_t         cur_pos;
+    TiVo_type       tivo_type;        /* TiVo type (SA / DTiVo) */
+    TiVo_series     tivo_series;      /* Series1 or Series2 */
+    TiVo_audio      audio_type;       /* AC3 or MPEG */
+    int             pes_length;       /* Length of Audio PES header */
+    int             pts_offset;       /* offset into audio PES of PTS */
+    uint8_t         pes_buffer[20];   /* holds incomplete pes headers */
+    int             pes_buf_cnt;      /* how many bytes in our buffer */
+    size_t          ac3_pkt_size;     /* length of ac3 pkt we've seen so far */
+    uint64_t        last_ty_pts;      /* last TY timestamp we've seen */
+    unsigned        seq_table_size;   /* number of entries in SEQ table */
+
+    int64_t         first_audio_pts;
+    int64_t         last_audio_pts;
+    int64_t         last_video_pts;
+
+    TyRecHdr       *rec_hdrs;         /* record headers array */
+    int             cur_rec;          /* current record in this chunk */
+    int             num_recs;         /* number of recs in this chunk */
+    int             seq_rec;          /* record number where seq start is */
+    TySeqTable     *seq_table;        /* table of SEQ entries from mstr chk */
+    int             first_chunk;
+
+    uint8_t         chunk[CHUNK_SIZE];
+} TYDemuxContext;
+
+static int ty_probe(AVProbeData *p)
+{
+    if (AV_RB32(p->buf) == TIVO_PES_FILEID &&
+        AV_RB32(p->buf + 4) == 0x02 &&
+        AV_RB32(p->buf + 8) == CHUNK_SIZE) {
+        return AVPROBE_SCORE_MAX;
+    }
+    return 0;
+}
+
+static TyRecHdr *parse_chunk_headers(const uint8_t *buf,
+                                     int num_recs)
+{
+    TyRecHdr *hdrs, *rec_hdr;
+    int i;
+
+    hdrs = av_calloc(num_recs, sizeof(TyRecHdr));
+    if (!hdrs)
+        return NULL;
+
+    for (i = 0; i < num_recs; i++) {
+        const uint8_t *record_header = buf + (i * 16);
+
+        rec_hdr = &hdrs[i];     /* for brevity */
+        rec_hdr->rec_type = record_header[3];
+        rec_hdr->subrec_type = record_header[2] & 0x0f;
+        if ((record_header[0] & 0x80) == 0x80) {
+            uint8_t b1, b2;
+
+            /* marker bit 2 set, so read extended data */
+            b1 = (((record_header[0] & 0x0f) << 4) |
+                  ((record_header[1] & 0xf0) >> 4));
+            b2 = (((record_header[1] & 0x0f) << 4) |
+                  ((record_header[2] & 0xf0) >> 4));
+
+            rec_hdr->ex[0] = b1;
+            rec_hdr->ex[1] = b2;
+            rec_hdr->rec_size = 0;
+            rec_hdr->ty_pts = 0;
+        } else {
+            rec_hdr->rec_size = (record_header[0] << 8 |
+                                 record_header[1]) << 4 |
+                                (record_header[2] >> 4);
+            rec_hdr->ty_pts = AV_RB64(&record_header[8]);
+        }
+    }
+    return hdrs;
+}
+
+static int find_es_header(const uint8_t *header,
+                          const uint8_t *buffer, int search_len)
+{
+    int count;
+
+    for (count = 0; count < search_len; count++) {
+        if (!memcmp(&buffer[count], header, 4))
+            return count;
+    }
+    return -1;
+}
+
+static int analyze_chunk(AVFormatContext *s, const uint8_t *chunk)
+{
+    TYDemuxContext *ty = s->priv_data;
+    int num_recs, i;
+    TyRecHdr *hdrs;
+    int num_6e0, num_be0, num_9c0, num_3c0;
+
+    /* skip if it's a Part header */
+    if (AV_RB32(&chunk[0]) == TIVO_PES_FILEID)
+        return 0;
+
+    /* number of records in chunk (we ignore high order byte;
+     * rarely are there > 256 chunks & we don't need that many anyway) */
+    num_recs = chunk[0];
+    if (num_recs < 5) {
+        /* try again with the next chunk.  Sometimes there are dead ones */
+        return 0;
+    }
+
+    chunk += 4;       /* skip past rec count & SEQ bytes */
+    ff_dlog(s, "probe: chunk has %d recs\n", num_recs);
+    hdrs = parse_chunk_headers(chunk, num_recs);
+    if (!hdrs)
+        return AVERROR(ENOMEM);
+
+    /* scan headers.
+     * 1. check video packets.  Presence of 0x6e0 means S1.
+     *    No 6e0 but have be0 means S2.
+     * 2. probe for audio 0x9c0 vs 0x3c0 (AC3 vs Mpeg)
+     *    If AC-3, then we have DTivo.
+     *    If MPEG, search for PTS offset.  This will determine SA vs. DTivo.
+     */
+    num_6e0 = num_be0 = num_9c0 = num_3c0 = 0;
+    for (i = 0; i < num_recs; i++) {
+        switch (hdrs[i].subrec_type << 8 | hdrs[i].rec_type) {
+        case 0x6e0:
+            num_6e0++;
+            break;
+        case 0xbe0:
+            num_be0++;
+            break;
+        case 0x3c0:
+            num_3c0++;
+            break;
+        case 0x9c0:
+            num_9c0++;
+            break;
+        }
+    }
+    ff_dlog(s, "probe: chunk has %d 0x6e0 recs, %d 0xbe0 recs.\n",
+            num_6e0, num_be0);
+
+    /* set up our variables */
+    if (num_6e0 > 0) {
+        ff_dlog(s, "detected Series 1 Tivo\n");
+        ty->tivo_series = TIVO_SERIES1;
+        ty->pes_length = SERIES1_PES_LENGTH;
+    } else if (num_be0 > 0) {
+        ff_dlog(s, "detected Series 2 Tivo\n");
+        ty->tivo_series = TIVO_SERIES2;
+        ty->pes_length = SERIES2_PES_LENGTH;
+    }
+    if (num_9c0 > 0) {
+        ff_dlog(s, "detected AC-3 Audio (DTivo)\n");
+        ty->audio_type = TIVO_AUDIO_AC3;
+        ty->tivo_type = TIVO_TYPE_DTIVO;
+        ty->pts_offset = AC3_PTS_OFFSET;
+        ty->pes_length = AC3_PES_LENGTH;
+    } else if (num_3c0 > 0) {
+        ty->audio_type = TIVO_AUDIO_MPEG;
+        ff_dlog(s, "detected MPEG Audio\n");
+    }
+
+    /* if tivo_type still unknown, we can check PTS location
+     * in MPEG packets to determine tivo_type */
+    if (ty->tivo_type == TIVO_TYPE_UNKNOWN) {
+        uint32_t data_offset = 16 * num_recs;
+        for (i = 0; i < num_recs; i++) {
+            if ((hdrs[i].subrec_type << 0x08 | hdrs[i].rec_type) == 0x3c0 && hdrs[i].rec_size > 15) {
+                /* first make sure we're aligned */
+                int pes_offset = find_es_header(ty_MPEGAudioPacket,
+                        &chunk[data_offset], 5);
+                if (pes_offset >= 0) {
+                    /* pes found. on SA, PES has hdr data at offset 6, not PTS. */
+                    if ((chunk[data_offset + 6 + pes_offset] & 0x80) == 0x80) {
+                        /* S1SA or S2(any) Mpeg Audio (PES hdr, not a PTS start) */
+                        if (ty->tivo_series == TIVO_SERIES1)
+                            ff_dlog(s, "detected Stand-Alone Tivo\n");
+                        ty->tivo_type = TIVO_TYPE_SA;
+                        ty->pts_offset = SA_PTS_OFFSET;
+                    } else {
+                        if (ty->tivo_series == TIVO_SERIES1)
+                            ff_dlog(s, "detected DirecTV Tivo\n");
+                        ty->tivo_type = TIVO_TYPE_DTIVO;
+                        ty->pts_offset = DTIVO_PTS_OFFSET;
+                    }
+                    break;
+                }
+            }
+            data_offset += hdrs[i].rec_size;
+        }
+    }
+    av_free(hdrs);
+
+    return 0;
+}
+
+static int ty_read_header(AVFormatContext *s)
+{
+    TYDemuxContext *ty = s->priv_data;
+    AVIOContext *pb = s->pb;
+    AVStream *st, *ast;
+    int i, ret = 0;
+
+    ty->first_audio_pts = AV_NOPTS_VALUE;
+    ty->last_audio_pts = AV_NOPTS_VALUE;
+    ty->last_video_pts = AV_NOPTS_VALUE;
+
+    for (i = 0; i < CHUNK_PEEK_COUNT; i++) {
+        avio_read(pb, ty->chunk, CHUNK_SIZE);
+
+        ret = analyze_chunk(s, ty->chunk);
+        if (ret < 0)
+            return ret;
+        if (ty->tivo_series != TIVO_SERIES_UNKNOWN &&
+            ty->audio_type  != TIVO_AUDIO_UNKNOWN &&
+            ty->tivo_type   != TIVO_TYPE_UNKNOWN)
+            break;
+    }
+
+    if (ty->tivo_series == TIVO_SERIES_UNKNOWN ||
+        ty->audio_type == TIVO_AUDIO_UNKNOWN ||
+        ty->tivo_type == TIVO_TYPE_UNKNOWN)
+        return AVERROR(EIO);
+
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
+    st->codecpar->codec_id   = AV_CODEC_ID_MPEG2VIDEO;
+    st->need_parsing         = AVSTREAM_PARSE_FULL_RAW;
+    avpriv_set_pts_info(st, 64, 1, 90000);
+
+    ast = avformat_new_stream(s, NULL);
+    if (!ast)
+        return AVERROR(ENOMEM);
+    ast->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
+
+    if (ty->audio_type == TIVO_AUDIO_MPEG) {
+        ast->codecpar->codec_id = AV_CODEC_ID_MP2;
+        ast->need_parsing       = AVSTREAM_PARSE_FULL_RAW;
+    } else {
+        ast->codecpar->codec_id = AV_CODEC_ID_AC3;
+    }
+    avpriv_set_pts_info(ast, 64, 1, 90000);
+
+    ty->first_chunk = 1;
+
+    avio_seek(pb, 0, SEEK_SET);
+
+    return 0;
+}
+
+/* parse a master chunk, filling the SEQ table and other variables.
+ * We assume the stream is currently pointing to it.
+ */
+static void parse_master(AVFormatContext *s)
+{
+    TYDemuxContext *ty = s->priv_data;
+    unsigned map_size;  /* size of bitmask, in bytes */
+    unsigned i, j;
+
+    /* Note that the entries in the SEQ table in the stream may have
+       different sizes depending on the bits per entry.  We store them
+       all in the same size structure, so we have to parse them out one
+       by one.  If we had a dynamic structure, we could simply read the
+       entire table directly from the stream into memory in place. */
+
+    /* clear the SEQ table */
+    av_freep(&ty->seq_table);
+
+    /* parse header info */
+
+    map_size = AV_RB32(ty->chunk + 20);  /* size of bitmask, in bytes */
+    i = AV_RB32(ty->chunk + 28);   /* size of SEQ table, in bytes */
+
+    ty->seq_table_size = i / (8LL + map_size);
+
+    if (ty->seq_table_size == 0) {
+        ty->seq_table = NULL;
+        return;
+    }
+
+    /* parse all the entries */
+    ty->seq_table = av_calloc(ty->seq_table_size, sizeof(TySeqTable));
+    if (ty->seq_table == NULL) {
+        ty->seq_table_size = 0;
+        return;
+    }
+
+    ty->cur_chunk_pos = 32;
+    for (j = 0; j < ty->seq_table_size; j++) {
+        ty->seq_table[j].timestamp = AV_RB64(ty->chunk + ty->cur_chunk_pos);
+        ty->cur_chunk_pos += 8;
+        if (map_size > 8) {
+            av_log(s, AV_LOG_ERROR, "Unsupported SEQ bitmap size in master chunk.\n");
+            ty->cur_chunk_pos += map_size;
+        } else {
+            memcpy(ty->seq_table[j].chunk_bitmask, ty->chunk + ty->cur_chunk_pos, map_size);
+        }
+    }
+}
+
+static int get_chunk(AVFormatContext *s)
+{
+    TYDemuxContext *ty = s->priv_data;
+    AVIOContext *pb = s->pb;
+    int read_size, num_recs;
+
+    ff_dlog(s, "parsing ty chunk #%d\n", ty->cur_chunk);
+
+    /* if we have left-over filler space from the last chunk, get that */
+    if (avio_feof(pb))
+        return AVERROR_EOF;
+
+    /* read the TY packet header */
+    read_size = avio_read(pb, ty->chunk, CHUNK_SIZE);
+    ty->cur_chunk++;
+
+    if ((read_size < 4) || (AV_RB32(ty->chunk) == 0)) {
+        return AVERROR_EOF;
+    }
+
+    /* check if it's a PART Header */
+    if (AV_RB32(ty->chunk) == TIVO_PES_FILEID) {
+        parse_master(s); /* parse master chunk */
+        return get_chunk(s);
+    }
+
+    /* number of records in chunk (8- or 16-bit number) */
+    if (ty->chunk[3] & 0x80) {
+        /* 16 bit rec cnt */
+        ty->num_recs = num_recs = (ty->chunk[1] << 8) + ty->chunk[0];
+        ty->seq_rec = (ty->chunk[3] << 8) + ty->chunk[2];
+        if (ty->seq_rec != 0xffff) {
+            ty->seq_rec &= ~0x8000;
+        }
+    } else {
+        /* 8 bit reclen - TiVo 1.3 format */
+        ty->num_recs = num_recs = ty->chunk[0];
+        ty->seq_rec = ty->chunk[1];
+    }
+    ty->cur_rec = 0;
+    ty->first_chunk = 0;
+
+    ff_dlog(s, "chunk has %d records\n", num_recs);
+    ty->cur_chunk_pos = 4;
+
+    av_freep(&ty->rec_hdrs);
+
+    if (num_recs * 16 >= CHUNK_SIZE - 4)
+        return AVERROR_INVALIDDATA;
+
+    ty->rec_hdrs = parse_chunk_headers(ty->chunk + 4, num_recs);
+    ty->cur_chunk_pos += 16 * num_recs;
+
+    return 0;
+}
+
+static int demux_video(AVFormatContext *s, TyRecHdr *rec_hdr, AVPacket *pkt)
+{
+    TYDemuxContext *ty = s->priv_data;
+    const int subrec_type = rec_hdr->subrec_type;
+    const int64_t rec_size = rec_hdr->rec_size;
+    int es_offset1;
+    int got_packet = 0;
+
+    if (subrec_type != 0x02 && subrec_type != 0x0c &&
+        subrec_type != 0x08 && rec_size > 4) {
+        /* get the PTS from this packet if it has one.
+         * on S1, only 0x06 has PES.  On S2, however, most all do.
+         * Do NOT Pass the PES Header to the MPEG2 codec */
+        es_offset1 = find_es_header(ty_VideoPacket, ty->chunk + ty->cur_chunk_pos, 5);
+        if (es_offset1 != -1) {
+            ty->last_video_pts = ff_parse_pes_pts(
+                    ty->chunk + ty->cur_chunk_pos + es_offset1 + VIDEO_PTS_OFFSET);
+            if (subrec_type != 0x06) {
+                /* if we found a PES, and it's not type 6, then we're S2 */
+                /* The packet will have video data (& other headers) so we
+                 * chop out the PES header and send the rest */
+                if (rec_size >= VIDEO_PES_LENGTH + es_offset1) {
+                    int size = rec_hdr->rec_size - VIDEO_PES_LENGTH - es_offset1;
+
+                    ty->cur_chunk_pos += VIDEO_PES_LENGTH + es_offset1;
+                    if (av_new_packet(pkt, size) < 0)
+                        return AVERROR(ENOMEM);
+                    memcpy(pkt->data, ty->chunk + ty->cur_chunk_pos, size);
+                    ty->cur_chunk_pos += size;
+                    pkt->stream_index = 0;
+                    got_packet = 1;
+                } else {
+                    ff_dlog(s, "video rec type 0x%02x has short PES"
+                        " (%"PRId64" bytes)\n", subrec_type, rec_size);
+                    /* nuke this block; it's too short, but has PES marker */
+                    ty->cur_chunk_pos += rec_size;
+                    return 0;
+                }
+            }
+        }
+    }
+
+    if (subrec_type == 0x06) {
+        /* type 6 (S1 DTivo) has no data, so we're done */
+        ty->cur_chunk_pos += rec_size;
+        return 0;
+    }
+
+    if (!got_packet) {
+        if (av_new_packet(pkt, rec_size) < 0)
+            return AVERROR(ENOMEM);
+        memcpy(pkt->data, ty->chunk + ty->cur_chunk_pos, rec_size);
+        ty->cur_chunk_pos += rec_size;
+        pkt->stream_index = 0;
+        got_packet = 1;
+    }
+
+    /* if it's not a continue blk, then set PTS */
+    if (subrec_type != 0x02) {
+        if (subrec_type == 0x0c && pkt->size >= 6)
+            pkt->data[5] |= 0x08;
+        if (subrec_type == 0x07) {
+            ty->last_ty_pts = rec_hdr->ty_pts;
+        } else {
+            /* yes I know this is a cheap hack.  It's the timestamp
+               used for display and skipping fwd/back, so it
+               doesn't have to be accurate to the millisecond.
+               I adjust it here by roughly one 1/30 sec.  Yes it
+               will be slightly off for UK streams, but it's OK.
+             */
+            ty->last_ty_pts += 35000000;
+            //ty->last_ty_pts += 33366667;
+        }
+        /* set PTS for this block before we send */
+        if (ty->last_video_pts > AV_NOPTS_VALUE) {
+            pkt->pts = ty->last_video_pts;
+            /* PTS gets used ONCE.
+             * Any subsequent frames we get BEFORE next PES
+             * header will have their PTS computed in the codec */
+            ty->last_video_pts = AV_NOPTS_VALUE;
+        }
+    }
+
+    return got_packet;
+}
+
+static int check_sync_pes(AVFormatContext *s, AVPacket *pkt,
+                          int32_t offset, int32_t rec_len)
+{
+    TYDemuxContext *ty = s->priv_data;
+
+    if (offset < 0 || offset + ty->pes_length > rec_len) {
+        /* entire PES header not present */
+        ff_dlog(s, "PES header at %d not complete in record. storing.\n", offset);
+        /* save the partial pes header */
+        if (offset < 0) {
+            /* no header found, fake some 00's (this works, believe me) */
+            memset(ty->pes_buffer, 0, 4);
+            ty->pes_buf_cnt = 4;
+            if (rec_len > 4)
+                ff_dlog(s, "PES header not found in record of %d bytes!\n", rec_len);
+            return -1;
+        }
+        /* copy the partial pes header we found */
+        memcpy(ty->pes_buffer, pkt->data + offset, rec_len - offset);
+        ty->pes_buf_cnt = rec_len - offset;
+
+        if (offset > 0) {
+            /* PES Header was found, but not complete, so trim the end of this record */
+            pkt->size -= rec_len - offset;
+            return 1;
+        }
+        return -1;    /* partial PES, no audio data */
+    }
+    /* full PES header present, extract PTS */
+    ty->last_audio_pts = ff_parse_pes_pts(&pkt->data[ offset + ty->pts_offset]);
+    if (ty->first_audio_pts == AV_NOPTS_VALUE)
+        ty->first_audio_pts = ty->last_audio_pts;
+    pkt->pts = ty->last_audio_pts;
+    memmove(pkt->data + offset, pkt->data + offset + ty->pes_length, rec_len - ty->pes_length);
+    pkt->size -= ty->pes_length;
+    return 0;
+}
+
+static int demux_audio(AVFormatContext *s, TyRecHdr *rec_hdr, AVPacket *pkt)
+{
+    TYDemuxContext *ty = s->priv_data;
+    const int subrec_type = rec_hdr->subrec_type;
+    const int64_t rec_size = rec_hdr->rec_size;
+    int es_offset1;
+
+    if (subrec_type == 2) {
+        int need = 0;
+        /* SA or DTiVo Audio Data, no PES (continued block)
+         * ================================================
+         */
+
+        /* continue PES if previous was incomplete */
+        if (ty->pes_buf_cnt > 0) {
+            need = ty->pes_length - ty->pes_buf_cnt;
+
+            ff_dlog(s, "continuing PES header\n");
+            /* do we have enough data to complete? */
+            if (need >= rec_size) {
+                /* don't have complete PES hdr; save what we have and return */
+                memcpy(ty->pes_buffer + ty->pes_buf_cnt, ty->chunk + ty->cur_chunk_pos, rec_size);
+                ty->cur_chunk_pos += rec_size;
+                ty->pes_buf_cnt += rec_size;
+                return 0;
+            }
+
+            /* we have enough; reconstruct this frame with the new hdr */
+            memcpy(ty->pes_buffer + ty->pes_buf_cnt, ty->chunk + ty->cur_chunk_pos, need);
+            ty->cur_chunk_pos += need;
+            /* get the PTS out of this PES header (MPEG or AC3) */
+            if (ty->audio_type == TIVO_AUDIO_MPEG) {
+                es_offset1 = find_es_header(ty_MPEGAudioPacket,
+                        ty->pes_buffer, 5);
+            } else {
+                es_offset1 = find_es_header(ty_AC3AudioPacket,
+                        ty->pes_buffer, 5);
+            }
+            if (es_offset1 < 0) {
+                ff_dlog(s, "Can't find audio PES header in packet.\n");
+            } else {
+                ty->last_audio_pts = ff_parse_pes_pts(
+                    &ty->pes_buffer[es_offset1 + ty->pts_offset]);
+                pkt->pts = ty->last_audio_pts;
+            }
+            ty->pes_buf_cnt = 0;
+
+        }
+        if (av_new_packet(pkt, rec_size - need) < 0)
+            return AVERROR(ENOMEM);
+        memcpy(pkt->data, ty->chunk + ty->cur_chunk_pos, rec_size - need);
+        ty->cur_chunk_pos += rec_size - need;
+        pkt->stream_index = 1;
+
+        /* S2 DTivo has AC3 packets with 2 padding bytes at end.  This is
+         * not allowed in the AC3 spec and will cause problems.  So here
+         * we try to trim things. */
+        /* Also, S1 DTivo has alternating short / long AC3 packets.  That
+         * is, one packet is short (incomplete) and the next packet has
+         * the first one's missing data, plus all of its own.  Strange. */
+        if (ty->audio_type == TIVO_AUDIO_AC3 &&
+                ty->tivo_series == TIVO_SERIES2) {
+            if (ty->ac3_pkt_size + pkt->size > AC3_PKT_LENGTH) {
+                pkt->size -= 2;
+                ty->ac3_pkt_size = 0;
+            } else {
+                ty->ac3_pkt_size += pkt->size;
+            }
+        }
+    } else if (subrec_type == 0x03) {
+        if (av_new_packet(pkt, rec_size) < 0)
+            return AVERROR(ENOMEM);
+        memcpy(pkt->data, ty->chunk + ty->cur_chunk_pos, rec_size);
+        ty->cur_chunk_pos += rec_size;
+        pkt->stream_index = 1;
+        /* MPEG Audio with PES Header, either SA or DTiVo   */
+        /* ================================================ */
+        es_offset1 = find_es_header(ty_MPEGAudioPacket, pkt->data, 5);
+
+        /* SA PES Header, No Audio Data                     */
+        /* ================================================ */
+        if ((es_offset1 == 0) && (rec_size == 16)) {
+            ty->last_audio_pts = ff_parse_pes_pts(&pkt->data[SA_PTS_OFFSET]);
+            if (ty->first_audio_pts == AV_NOPTS_VALUE)
+                ty->first_audio_pts = ty->last_audio_pts;
+            av_packet_unref(pkt);
+            return 0;
+        }
+        /* DTiVo Audio with PES Header                      */
+        /* ================================================ */
+
+        /* Check for complete PES */
+        if (check_sync_pes(s, pkt, es_offset1, rec_size) == -1) {
+            /* partial PES header found, nothing else.
+             * we're done. */
+            av_packet_unref(pkt);
+            return 0;
+        }
+    } else if (subrec_type == 0x04) {
+        /* SA Audio with no PES Header                      */
+        /* ================================================ */
+        if (av_new_packet(pkt, rec_size) < 0)
+            return AVERROR(ENOMEM);
+        memcpy(pkt->data, ty->chunk + ty->cur_chunk_pos, rec_size);
+        ty->cur_chunk_pos += rec_size;
+        pkt->stream_index = 1;
+        pkt->pts = ty->last_audio_pts;
+    } else if (subrec_type == 0x09) {
+        if (av_new_packet(pkt, rec_size) < 0)
+            return AVERROR(ENOMEM);
+        memcpy(pkt->data, ty->chunk + ty->cur_chunk_pos, rec_size);
+        ty->cur_chunk_pos += rec_size ;
+        pkt->stream_index = 1;
+
+        /* DTiVo AC3 Audio Data with PES Header             */
+        /* ================================================ */
+        es_offset1 = find_es_header(ty_AC3AudioPacket, pkt->data, 5);
+
+        /* Check for complete PES */
+        if (check_sync_pes(s, pkt, es_offset1, rec_size) == -1) {
+            /* partial PES header found, nothing else.  we're done. */
+            av_packet_unref(pkt);
+            return 0;
+        }
+        /* S2 DTivo has invalid long AC3 packets */
+        if (ty->tivo_series == TIVO_SERIES2) {
+            if (pkt->size > AC3_PKT_LENGTH) {
+                pkt->size -= 2;
+                ty->ac3_pkt_size = 0;
+            } else {
+                ty->ac3_pkt_size = pkt->size;
+            }
+        }
+    } else {
+        /* Unsupported/Unknown */
+        ty->cur_chunk_pos += rec_size;
+        return 0;
+    }
+
+    return 1;
+}
+
+static int ty_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    TYDemuxContext *ty = s->priv_data;
+    AVIOContext *pb = s->pb;
+    TyRecHdr *rec;
+    int64_t rec_size = 0;
+    int ret = 0;
+
+    if (avio_feof(pb))
+        return AVERROR_EOF;
+
+    while (ret <= 0) {
+        if (ty->first_chunk || ty->cur_rec >= ty->num_recs) {
+            if (get_chunk(s) < 0 || ty->num_recs == 0)
+                return AVERROR_EOF;
+        }
+
+        rec = &ty->rec_hdrs[ty->cur_rec];
+        rec_size = rec->rec_size;
+        ty->cur_rec++;
+
+        if (rec_size <= 0)
+            continue;
+
+        if (ty->cur_chunk_pos + rec->rec_size > CHUNK_SIZE)
+            return AVERROR_INVALIDDATA;
+
+        if (avio_feof(pb))
+            return AVERROR_EOF;
+
+        switch (rec->rec_type) {
+        case VIDEO_ID:
+            ret = demux_video(s, rec, pkt);
+            break;
+        case AUDIO_ID:
+            ret = demux_audio(s, rec, pkt);
+            break;
+        default:
+            ff_dlog(s, "Invalid record type 0x%02x\n", rec->rec_type);
+        case 0x01:
+        case 0x02:
+        case 0x03: /* TiVo data services */
+        case 0x05: /* unknown, but seen regularly */
+            ty->cur_chunk_pos += rec->rec_size;
+            break;
+        }
+    }
+
+    return 0;
+}
+
+AVInputFormat ff_ty_demuxer = {
+    .name           = "ty",
+    .long_name      = NULL_IF_CONFIG_SMALL("TiVo TY Stream"),
+    .priv_data_size = sizeof(TYDemuxContext),
+    .read_probe     = ty_probe,
+    .read_header    = ty_read_header,
+    .read_packet    = ty_read_packet,
+    .extensions     = "ty,ty+",
+    .flags          = AVFMT_TS_DISCONT,
+};