[FFmpeg-devel] avformat: add vividas demuxer

Submitted by Paul B Mahol on Dec. 15, 2018, 7:06 p.m.

Details

Message ID 20181215190643.24872-1-onemda@gmail.com
State New
Headers show

Commit Message

Paul B Mahol Dec. 15, 2018, 7:06 p.m.
Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavformat/Makefile     |   1 +
 libavformat/allformats.c |   1 +
 libavformat/vividas.c    | 715 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 717 insertions(+)
 create mode 100644 libavformat/vividas.c

Comments

Tomas Härdin Dec. 16, 2018, 9:03 p.m.
lör 2018-12-15 klockan 20:06 +0100 skrev Paul B Mahol:
> > Signed-off-by: Paul B Mahol <onemda@gmail.com>
> +
> +static void put_v(uint8_t *p, int v)

This should take unsigned

> +{
> +    if (v>>28)
> +        *p++ = ((v>>28)&0x7f)|0x80;
> +    if (v>>21)
> +        *p++ = ((v>>21)&0x7f)|0x80;
> +    if (v>>14)
> +        *p++ = ((v>>14)&0x7f)|0x80;
> +    if (v>>7)
> +        *p++ =  ((v>>7)&0x7f)|0x80;
> +}
> +
> +static unsigned int recover_key(unsigned char sample[4], int expected_size)

this too

> +{
> +    unsigned char plaintext[8] = { 'S', 'B' };
> +
> +    put_v(plaintext+2, expected_size);
> +
> +    return (sample[0]^plaintext[0])|
> +        ((sample[1]^plaintext[1])<<8)|
> +        ((sample[2]^plaintext[2])<<16)|
> +        ((sample[3]^plaintext[3])<<24);
> +}
> +
> +static void xor_block(void *p1, void *p2, int size, int key, int *key_ptr)

here as well

> +{
> +    int *d1 = p1;
> +    int *d2 = p2;
> +    int k = *key_ptr;
> +
> +    size >>= 2;
> +
> +    while (size--) {
> +        *d2 = *d1 ^ k;
> +        k += key;
> +        d1++;
> +        d2++;
> +    }
> +
> +    *key_ptr = k;
> +}
> +
> +static void decode_block(uint8_t *src, uint8_t *dest, int size,
> +                         uint32_t key, uint32_t *key_ptr,
> +                         int align)

and here

> +{
> +    int s = size;
> +    char tmp[4];
> +    int a2;
> +
> +    if (!size)
> +        return;
> +
> +    align &= 3;
> +    a2 = (4 - align) & 3;
> +
> +    if (align) {
> +        uint32_t tmpkey = *key_ptr - key;
> +        memcpy(tmp + align, src, a2);
> +        xor_block(tmp, tmp, 4, key, &tmpkey);
> +        memcpy(dest, tmp + align, a2);
> +        s -= a2;
> +    }
> +
> +    if (s >= 4) {
> +        if (!align)
> +            align = 4;
> +        xor_block(src + a2, dest + a2, s & ~3,
> +                  key, key_ptr);
> +        s &= 3;
> +    }
> +
> +    if (s) {
> +        size -= s;
> +        memcpy(tmp, src + size, s);
> +        xor_block(&tmp, &tmp, 4, key, key_ptr);
> +        memcpy(dest + size, tmp, s);
> +    }
> +}
> +

Becaaaause:

> +static uint32_t get_v(uint8_t *p)
> +{
> +    uint32_t v = 0;
> +
> +    do {
> +        if (v >= UINT_MAX / 128 - *p)
> +            return v;
> +        v <<= 7;
> +        v += *p & 0x7f;
> +    } while (*p++ & 0x80);
> +
> +    return v;

This may return values between INT_MAX+1 and UINT_MAX...

> +}
> +
> +static uint8_t *read_vblock(AVIOContext *src, uint32_t *size,
> +                            uint32_t key, uint32_t *k2, int align)
> +{
> +    uint8_t tmp[4];
> +    uint8_t *buf;
> +    unsigned n;
> +
> +    if (avio_read(src, tmp, 4) != 4)
> +        return NULL;
> +
> +    decode_block(tmp, tmp, 4, key, k2, align);
> +
> +    n = get_v(tmp);
> +    if (!n)
> +        return NULL;
> +
> +    buf = av_malloc(n);
> +    if (!buf)
> +        return NULL;
> +
> +    *size = n;
> +    n -= 4;
> +
> +    memcpy(buf, tmp, 4);
> +
> +    if (avio_read(src, buf + 4, n) == n) {
> +        decode_block(buf + 4, buf + 4, n, key, k2, align + 4);

which get passed in here ^
leading to undefined behavior

> +    } else {
> +        av_free(buf);
> +        buf = NULL;
> +    }
> +
> +    return buf;
> +}
> +
> +static uint8_t *read_sb_block(AVIOContext *src, unsigned *size,
> +                              uint32_t *key, int expected_size)

expected_size should be unsigned too.. And so on, I think you get the
picture

/Tomas

Patch hide | download patch | download mbox

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 0e43a12df5..c42ceb40c5 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -522,6 +522,7 @@  OBJS-$(CONFIG_VC1_DEMUXER)               += rawdec.o vc1dec.o
 OBJS-$(CONFIG_VC1_MUXER)                 += rawenc.o
 OBJS-$(CONFIG_VC1T_DEMUXER)              += vc1test.o
 OBJS-$(CONFIG_VC1T_MUXER)                += vc1testenc.o
+OBJS-$(CONFIG_VIVIDAS_DEMUXER)           += vividas.o
 OBJS-$(CONFIG_VIVO_DEMUXER)              += vivo.o
 OBJS-$(CONFIG_VMD_DEMUXER)               += sierravmd.o
 OBJS-$(CONFIG_VOBSUB_DEMUXER)            += subtitles.o # mpeg demuxer is in the dependencies
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index df83b04484..399625fd78 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -422,6 +422,7 @@  extern AVInputFormat  ff_vc1_demuxer;
 extern AVOutputFormat ff_vc1_muxer;
 extern AVInputFormat  ff_vc1t_demuxer;
 extern AVOutputFormat ff_vc1t_muxer;
+extern AVInputFormat  ff_vividas_demuxer;
 extern AVInputFormat  ff_vivo_demuxer;
 extern AVInputFormat  ff_vmd_demuxer;
 extern AVInputFormat  ff_vobsub_demuxer;
diff --git a/libavformat/vividas.c b/libavformat/vividas.c
new file mode 100644
index 0000000000..4e5b8540b4
--- /dev/null
+++ b/libavformat/vividas.c
@@ -0,0 +1,715 @@ 
+/*
+ * Vividas VIV format Demuxer
+ * Copyright (c) 2012 Krzysztof Klinikowski
+ * Copyright (c) 2010 Andrzej Szombierski
+ * based on vivparse Copyright (c) 2007 Måns Rullgård
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * @brief Vividas VIV (.viv) file demuxer
+ * @author Andrzej Szombierski [qq at kuku eu org] (2010-07)
+ * @sa http://wiki.multimedia.cx/index.php?title=Vividas_VIV
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avio_internal.h"
+#include "avformat.h"
+
+#define MAX_AUDIO_SUBPACKETS 100
+
+typedef struct VIV_SB_block {
+    int size, n_packets;
+    int64_t byte_offset;
+    int64_t packet_offset;
+} VIV_SB_block;
+
+typedef struct VIV_SB_entry {
+    int size, flag;
+} VIV_SB_entry;
+
+typedef struct VIV_AudioSubpacket {
+    int start, pcm_bytes;
+} VIV_AudioSubpacket;
+
+typedef struct VividasDemuxContext {
+    int n_sb_blocks;
+    VIV_SB_block *sb_blocks;
+
+    uint32_t sb_key;
+    int64_t sb_offset;
+
+    int current_sb, current_sb_entry;
+    uint8_t *sb_buf;
+    AVIOContext *sb_pb;
+    int n_sb_entries;
+    VIV_SB_entry *sb_entries;
+
+    int n_audio_subpackets;
+    int current_audio_subpacket;
+
+    int64_t audio_sample;
+
+    VIV_AudioSubpacket audio_subpackets[MAX_AUDIO_SUBPACKETS];
+} VividasDemuxContext;
+
+static int viv_probe(AVProbeData *p)
+{
+    if (memcmp(p->buf, "vividas03", 9))
+        return 0;
+
+    return AVPROBE_SCORE_MAX;
+}
+
+static const unsigned short keybits[32] = {
+     163,  416,  893,   82,  223,  572, 1137,  430,
+     659, 1104,   13,  626,  695,  972, 1465,  686,
+     843, 1216,  317, 1122, 1383,   92,  513, 1158,
+    1243,   48,  573, 1306, 1495,  396, 1009,  350,
+};
+
+static uint32_t decode_key(uint8_t  *buf)
+{
+    uint32_t key = 0;
+
+    for (int i = 0; i < 32; i++) {
+        unsigned p = keybits[i];
+        key |= !!(buf[p>>3] & (1<<(p&7))) << i;
+    }
+
+    return key;
+}
+
+static void put_v(uint8_t *p, int v)
+{
+    if (v>>28)
+        *p++ = ((v>>28)&0x7f)|0x80;
+    if (v>>21)
+        *p++ = ((v>>21)&0x7f)|0x80;
+    if (v>>14)
+        *p++ = ((v>>14)&0x7f)|0x80;
+    if (v>>7)
+        *p++ =  ((v>>7)&0x7f)|0x80;
+}
+
+static unsigned int recover_key(unsigned char sample[4], int expected_size)
+{
+    unsigned char plaintext[8] = { 'S', 'B' };
+
+    put_v(plaintext+2, expected_size);
+
+    return (sample[0]^plaintext[0])|
+        ((sample[1]^plaintext[1])<<8)|
+        ((sample[2]^plaintext[2])<<16)|
+        ((sample[3]^plaintext[3])<<24);
+}
+
+static void xor_block(void *p1, void *p2, int size, int key, int *key_ptr)
+{
+    int *d1 = p1;
+    int *d2 = p2;
+    int k = *key_ptr;
+
+    size >>= 2;
+
+    while (size--) {
+        *d2 = *d1 ^ k;
+        k += key;
+        d1++;
+        d2++;
+    }
+
+    *key_ptr = k;
+}
+
+static void decode_block(uint8_t *src, uint8_t *dest, int size,
+                         uint32_t key, uint32_t *key_ptr,
+                         int align)
+{
+    int s = size;
+    char tmp[4];
+    int a2;
+
+    if (!size)
+        return;
+
+    align &= 3;
+    a2 = (4 - align) & 3;
+
+    if (align) {
+        uint32_t tmpkey = *key_ptr - key;
+        memcpy(tmp + align, src, a2);
+        xor_block(tmp, tmp, 4, key, &tmpkey);
+        memcpy(dest, tmp + align, a2);
+        s -= a2;
+    }
+
+    if (s >= 4) {
+        if (!align)
+            align = 4;
+        xor_block(src + a2, dest + a2, s & ~3,
+                  key, key_ptr);
+        s &= 3;
+    }
+
+    if (s) {
+        size -= s;
+        memcpy(tmp, src + size, s);
+        xor_block(&tmp, &tmp, 4, key, key_ptr);
+        memcpy(dest + size, tmp, s);
+    }
+}
+
+static uint32_t get_v(uint8_t *p)
+{
+    uint32_t v = 0;
+
+    do {
+        if (v >= UINT_MAX / 128 - *p)
+            return v;
+        v <<= 7;
+        v += *p & 0x7f;
+    } while (*p++ & 0x80);
+
+    return v;
+}
+
+static uint8_t *read_vblock(AVIOContext *src, uint32_t *size,
+                            uint32_t key, uint32_t *k2, int align)
+{
+    uint8_t tmp[4];
+    uint8_t *buf;
+    unsigned n;
+
+    if (avio_read(src, tmp, 4) != 4)
+        return NULL;
+
+    decode_block(tmp, tmp, 4, key, k2, align);
+
+    n = get_v(tmp);
+    if (!n)
+        return NULL;
+
+    buf = av_malloc(n);
+    if (!buf)
+        return NULL;
+
+    *size = n;
+    n -= 4;
+
+    memcpy(buf, tmp, 4);
+
+    if (avio_read(src, buf + 4, n) == n) {
+        decode_block(buf + 4, buf + 4, n, key, k2, align + 4);
+    } else {
+        av_free(buf);
+        buf = NULL;
+    }
+
+    return buf;
+}
+
+static uint8_t *read_sb_block(AVIOContext *src, unsigned *size,
+                              uint32_t *key, int expected_size)
+{
+    uint8_t *buf;
+    uint8_t ibuf[8], sbuf[8];
+    uint32_t k2;
+    int n;
+
+    if (avio_read(src, ibuf, 8) < 8)
+        return NULL;
+
+    k2 = *key;
+    decode_block(ibuf, sbuf, 8, *key, &k2, 0);
+
+    n = get_v(sbuf+2);
+
+    if (sbuf[0] != 'S' || sbuf[1] != 'B' || (expected_size>0 && n != expected_size)) {
+        uint32_t tmpkey = recover_key(ibuf, expected_size);
+        k2 = tmpkey;
+        decode_block(ibuf, sbuf, 8, tmpkey, &k2, 0);
+        n = get_v(sbuf+2);
+        if (sbuf[0] != 'S' || sbuf[1] != 'B' || expected_size != n)
+            return NULL;
+        *key = tmpkey;
+    }
+
+    buf = av_malloc(n);
+    if (!buf)
+        return NULL;
+
+    memcpy(buf, sbuf, 8);
+
+    *size = n;
+    n -= 8;
+
+    if (avio_read(src, buf+8, n) < n) {
+        av_free(buf);
+        return NULL;
+    }
+
+    decode_block(buf + 8, buf + 8, n, *key, &k2, 0);
+
+    return buf;
+}
+
+static void track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *buf, int size)
+{
+    int i,j;
+    int64_t off;
+    int val_1;
+    int num_video, num_audio;
+    AVIOContext *pb;
+
+    pb = avio_alloc_context(buf, size, 0, NULL, NULL, NULL, NULL);
+    if (!pb)
+        return;
+
+    ffio_read_varlen(pb); // track_header_len
+    avio_r8(pb); // '1'
+
+    val_1 = ffio_read_varlen(pb);
+
+    for (i=0;i<val_1;i++) {
+        int c = avio_r8(pb);
+        for (j=0;j<c;j++) {
+            avio_r8(pb); // val_3
+            avio_r8(pb); // val_4
+        }
+    }
+
+    avio_r8(pb); // num_streams
+
+    off = avio_tell(pb);
+    off += ffio_read_varlen(pb); // val_5
+
+    avio_r8(pb); // '2'
+    num_video = avio_r8(pb);
+
+    avio_seek(pb, off, SEEK_SET);
+    if (num_video != 1)
+        av_log(s, AV_LOG_WARNING, "number of video tracks %d is not 1\n", num_video);
+
+    for (i = 0; i < num_video; i++) {
+        AVStream *st = avformat_new_stream(s, NULL);
+
+        st->id = i;
+
+        st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
+        st->codecpar->codec_id = AV_CODEC_ID_VP6;
+
+        off = avio_tell(pb);
+        off += ffio_read_varlen(pb);
+        avio_r8(pb); // '3'
+        avio_r8(pb); // val_7
+        st->time_base.num = avio_rl32(pb); // frame_time
+        st->time_base.den = avio_rl32(pb); // time_base
+        st->nb_frames = avio_rl32(pb); // n frames
+        st->codecpar->width = avio_rl16(pb); // width
+        st->codecpar->height = avio_rl16(pb); // height
+        avio_r8(pb); // val_8
+        avio_rl32(pb); // val_9
+
+        avio_seek(pb, off, SEEK_SET);
+    }
+
+    off = avio_tell(pb);
+    off += ffio_read_varlen(pb); // val_10
+    avio_r8(pb); // '4'
+    num_audio = avio_r8(pb);
+    avio_seek(pb, off, SEEK_SET);
+
+    if (num_audio != 1)
+        av_log(s, AV_LOG_WARNING, "number of audio tracks %d is not 1\n", num_audio);
+
+    for(i=0;i<num_audio;i++) {
+        int q;
+        AVStream *st = avformat_new_stream(s, NULL);
+
+        st->id = num_video + i;
+
+        st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
+        st->codecpar->codec_id = AV_CODEC_ID_VORBIS;
+
+        off = avio_tell(pb);
+        off += ffio_read_varlen(pb); // length
+        avio_r8(pb); // '5'
+        avio_r8(pb); //codec_id
+        avio_rl16(pb); //codec_subid
+        st->codecpar->channels = avio_rl16(pb); // channels
+        st->codecpar->sample_rate = avio_rl32(pb); // sample_rate
+        avio_seek(pb, 10, SEEK_CUR); // data_1
+        q = avio_r8(pb);
+        avio_seek(pb, q, SEEK_CUR); // data_2
+        avio_r8(pb); // zeropad
+
+        if (avio_tell(pb) < off) {
+            int num_data;
+            int xd_size = 0;
+            int data_len[256];
+            uint8_t * p;
+            int offset = 1;
+            ffio_read_varlen(pb); // val_13
+            avio_r8(pb); // '19'
+            ffio_read_varlen(pb); // len_3
+            num_data = avio_r8(pb);
+            for(j=0;j<num_data;j++) {
+                data_len[j] = ffio_read_varlen(pb);
+                xd_size += data_len[j];
+            }
+
+            st->codecpar->extradata_size = 64 + xd_size + xd_size / 255;
+            st->codecpar->extradata = (uint8_t*)av_mallocz(st->codecpar->extradata_size);
+
+            p = st->codecpar->extradata;
+            p[0] = 2;
+
+            for (j = 0; j < num_data - 1; j++)
+                offset += av_xiphlacing(&p[offset], data_len[j]);
+
+            for (j = 0; j < num_data; j++) {
+                avio_read(pb, &p[offset], data_len[j]);
+                offset += data_len[j];
+            }
+
+            st->codecpar->extradata_size = offset;
+        }
+    }
+
+    av_free(pb);
+}
+
+static void track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *buf, int size)
+{
+    int64_t off;
+    int64_t poff;
+    int maxnp=0;
+    AVIOContext *pb;
+    int i;
+
+    pb = avio_alloc_context(buf, size, 0, NULL, NULL, NULL, NULL);
+    if (!pb)
+        return;
+
+    ffio_read_varlen(pb); // track_index_len
+    avio_r8(pb); // 'c'
+    viv->n_sb_blocks = ffio_read_varlen(pb);
+    viv->sb_blocks = av_calloc(viv->n_sb_blocks, sizeof(VIV_SB_block));
+    if (!viv->sb_blocks) {
+        viv->n_sb_blocks = 0;
+        av_free(pb);
+        return;
+    }
+
+    off = 0;
+    poff = 0;
+
+    for (i = 0; i < viv->n_sb_blocks; i++) {
+        viv->sb_blocks[i].byte_offset = off;
+        viv->sb_blocks[i].packet_offset = poff;
+
+        viv->sb_blocks[i].size = ffio_read_varlen(pb);
+        viv->sb_blocks[i].n_packets = ffio_read_varlen(pb);
+
+        off += viv->sb_blocks[i].size;
+        poff += viv->sb_blocks[i].n_packets;
+
+
+        if (maxnp < viv->sb_blocks[i].n_packets)
+            maxnp = viv->sb_blocks[i].n_packets;
+    }
+
+    viv->sb_entries = av_calloc(maxnp, sizeof(VIV_SB_entry));
+    av_free(pb);
+}
+
+static void load_sb_block(AVFormatContext *s, VividasDemuxContext *viv, int expected_size)
+{
+    uint32_t size=0;
+    int i;
+    AVIOContext *pb = 0;
+
+    if (viv->sb_pb) {
+        av_free(viv->sb_pb);
+        viv->sb_pb = NULL;
+    }
+
+    if (viv->sb_buf)
+        av_free(viv->sb_buf);
+
+    viv->sb_buf = read_sb_block(s->pb, &size, &viv->sb_key, expected_size);
+    if (!viv->sb_buf) {
+        return;
+    }
+
+    pb = avio_alloc_context(viv->sb_buf, size, 0, NULL, NULL, NULL, NULL);
+    if (!pb)
+        return;
+
+    viv->sb_pb = pb;
+
+    avio_r8(pb); //  'S'
+    avio_r8(pb); //  'B'
+    ffio_read_varlen(pb); //  size
+    avio_r8(pb); //  junk
+    ffio_read_varlen(pb); // first packet
+
+    viv->n_sb_entries = viv->sb_blocks[viv->current_sb].n_packets;
+
+    for (i = 0; i < viv->n_sb_entries; i++) {
+        viv->sb_entries[i].size = ffio_read_varlen(pb);
+        viv->sb_entries[i].flag = avio_r8(pb);
+    }
+
+    ffio_read_varlen(pb);
+    avio_r8(pb);
+
+    viv->current_sb_entry = 0;
+}
+
+static int viv_read_header(AVFormatContext *s)
+{
+    VividasDemuxContext *viv = s->priv_data;
+    AVIOContext *pb = s->pb;
+    int64_t header_end;
+    int num_tracks;
+    uint32_t key, k2;
+    uint32_t v;
+    uint8_t keybuffer[187];
+    uint32_t b22_size = 0;
+    uint32_t b22_key = 0;
+    uint8_t *buf = 0;
+
+    avio_skip(pb, 9);
+
+    header_end = avio_tell(pb);
+
+    header_end += ffio_read_varlen(pb);
+
+    num_tracks = avio_r8(pb);
+
+    if (num_tracks != 1) {
+        av_log(s, AV_LOG_ERROR, "number of tracks %d is not 1\n", num_tracks);
+        return AVERROR(EINVAL);
+    }
+
+    v = avio_r8(pb);
+    avio_seek(pb, v, SEEK_CUR);
+
+    avio_read(pb, keybuffer, 187);
+    key = decode_key(keybuffer);
+    viv->sb_key = key;
+
+    avio_rl32(pb);
+
+    for (;;) {
+        int64_t here = avio_tell(pb);
+        int block_len, block_type;
+
+        if (here >= header_end)
+            break;
+
+        block_len = ffio_read_varlen(pb);
+        block_type = avio_r8(pb);
+
+        if (block_type == 22) {
+            avio_read(pb, keybuffer, 187);
+            b22_key = decode_key(keybuffer);
+            b22_size = avio_rl32(pb);
+        }
+
+        avio_seek(pb, here + block_len, SEEK_SET);
+    }
+
+    if (b22_size) {
+        k2 = b22_key;
+        buf = read_vblock(pb, &v, b22_key, &k2, 0);
+        if (!buf)
+            return AVERROR(EIO);
+
+        av_free(buf);
+    }
+
+    k2 = key;
+    buf = read_vblock(pb, &v, key, &k2, 0);
+    if (!buf)
+        return AVERROR(EIO);
+    track_header(viv, s, buf, v);
+    av_free(buf);
+
+    buf = read_vblock(pb, &v, key, &k2, v);
+    if (!buf)
+        return AVERROR(EIO);
+    track_index(viv, s, buf, v);
+    av_free(buf);
+
+    viv->sb_offset = avio_tell(pb);
+    if (viv->n_sb_blocks > 0) {
+        viv->current_sb = 0;
+        load_sb_block(s, viv, viv->sb_blocks[0].size);
+    } else {
+        viv->current_sb = -1;
+    }
+
+    return 0;
+}
+
+static int viv_read_packet(AVFormatContext *s,
+                           AVPacket *pkt)
+{
+    VividasDemuxContext *viv = s->priv_data;
+    AVIOContext *pb;
+    int64_t off;
+    int ret;
+
+    if (avio_feof(viv->sb_pb))
+        return AVERROR_EOF;
+
+    if (viv->current_audio_subpacket < viv->n_audio_subpackets) {
+        AVStream *astream;
+        int size = viv->audio_subpackets[viv->current_audio_subpacket+1].start - viv->audio_subpackets[viv->current_audio_subpacket].start;
+
+        pb = viv->sb_pb;
+        ret = av_get_packet(pb, pkt, size);
+        if (ret < 0)
+            return ret;
+        pkt->pos += viv->sb_offset + viv->sb_blocks[viv->current_sb].byte_offset;
+
+        pkt->stream_index = 1;
+        astream = s->streams[pkt->stream_index];
+
+        pkt->pts = av_rescale(viv->audio_sample, astream->time_base.den, astream->time_base.num) / astream->codecpar->sample_rate;
+        viv->audio_sample += viv->audio_subpackets[viv->current_audio_subpacket].pcm_bytes / 2 / astream->codecpar->channels;
+        pkt->flags |= AV_PKT_FLAG_KEY;
+        viv->current_audio_subpacket++;
+        return 0;
+    }
+
+    if (viv->current_sb_entry >= viv->n_sb_entries) {
+        if (viv->current_sb+1 >= viv->n_sb_blocks)
+            return AVERROR(EIO);
+        viv->current_sb++;
+
+        load_sb_block(s, viv, 0);
+        viv->current_sb_entry = 0;
+    }
+
+    pb = viv->sb_pb;
+    off = avio_tell(pb);
+    off += viv->sb_entries[viv->current_sb_entry].size;
+
+    if (viv->sb_entries[viv->current_sb_entry].flag == 0) {
+        int i, v_size = ffio_read_varlen(pb);
+
+        ffio_read_varlen(pb);
+        ret = av_get_packet(pb, pkt, v_size);
+        if (ret < 0)
+            return ret;
+        pkt->pos += viv->sb_offset + viv->sb_blocks[viv->current_sb].byte_offset;
+
+        pkt->pts = viv->sb_blocks[viv->current_sb].packet_offset + viv->current_sb_entry;
+        pkt->flags |= (pkt->data[0]&0x80)?0:AV_PKT_FLAG_KEY;
+        pkt->stream_index = 0;
+
+        for (i = 0; i < MAX_AUDIO_SUBPACKETS - 1; i++) {
+            int start, pcm_bytes;
+            start = ffio_read_varlen(pb);
+            pcm_bytes = ffio_read_varlen(pb);
+
+            if (i > 0 && start == 0)
+                break;
+
+            viv->n_audio_subpackets = i+1;
+            viv->audio_subpackets[i].start = start;
+            viv->audio_subpackets[i].pcm_bytes = pcm_bytes;
+        }
+        viv->audio_subpackets[viv->n_audio_subpackets].start = (int)(off - avio_tell(pb));
+        viv->current_audio_subpacket = 0;
+
+    } else {
+        int v_size = ffio_read_varlen(pb);
+
+        ret = av_get_packet(pb, pkt, v_size);
+        if (ret < 0)
+            return ret;
+        pkt->pos += viv->sb_offset + viv->sb_blocks[viv->current_sb].byte_offset;
+        pkt->pts = viv->sb_blocks[viv->current_sb].packet_offset + viv->current_sb_entry;
+        pkt->flags |= (pkt->data[0]&0x80)?0:AV_PKT_FLAG_KEY;
+        pkt->stream_index = 0;
+    }
+
+    viv->current_sb_entry++;
+
+    return 0;
+}
+
+static int viv_read_close(AVFormatContext *s)
+{
+    VividasDemuxContext *viv = s->priv_data;
+
+    av_freep(&viv->sb_pb);
+    av_freep(&viv->sb_buf);
+    av_freep(&viv->sb_blocks);
+    av_freep(&viv->sb_entries);
+
+    return 0;
+}
+
+static int viv_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
+{
+    VividasDemuxContext *viv = s->priv_data;
+    int64_t frame;
+
+    if (stream_index == 0)
+        frame = timestamp;
+    else
+        frame = av_rescale_q(timestamp, s->streams[0]->time_base, s->streams[stream_index]->time_base);
+
+    for (int i = 0; i < viv->n_sb_blocks; i++) {
+        if (frame >= viv->sb_blocks[i].packet_offset && frame < viv->sb_blocks[i].packet_offset + viv->sb_blocks[i].n_packets) {
+            // flush audio packet queue
+            viv->current_audio_subpacket = 0;
+            viv->n_audio_subpackets = 0;
+            viv->current_sb = i;
+            // seek to ith sb block
+            avio_seek(s->pb, viv->sb_offset + viv->sb_blocks[i].byte_offset, SEEK_SET);
+            // load the block
+            load_sb_block(s, viv, 0);
+            // most problematic part: guess audio offset
+            viv->audio_sample = av_rescale_q(viv->sb_blocks[i].packet_offset, av_make_q(s->streams[1]->codecpar->sample_rate, 1), av_inv_q(s->streams[0]->time_base));
+            // hand-tuned 1.s a/v offset
+            viv->audio_sample += s->streams[1]->codecpar->sample_rate;
+            viv->current_sb_entry = 0;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+AVInputFormat ff_vividas_demuxer = {
+    .name           = "vividas",
+    .long_name      = NULL_IF_CONFIG_SMALL("Vividas VIV"),
+    .priv_data_size = sizeof(VividasDemuxContext),
+    .read_probe     = viv_probe,
+    .read_header    = viv_read_header,
+    .read_packet    = viv_read_packet,
+    .read_close     = viv_read_close,
+    .read_seek      = viv_read_seek,
+};