cat file1.ts file2.ts file3.ts | avconv -f mpegts -i - -ss 00:01:00.000 -acodec copy -vcodec copy -vframes 1525 -f vob -y file.mpg

avconv version v0.7-1795-g8ef79f4, Copyright (c) 2000-2011 the Libav developers
  built on Nov 10 2011 13:01:23 with gcc 4.5.3
[mp3 @ 0x63eee0] Header missing
[mpegts @ 0x61f7c0] max_analyze_duration reached
[mpegts @ 0x61f7c0] Estimating duration from bitrate, this may be inaccurate
Input #0, mpegts, from 'pipe:':
  Duration: N/A, start: 94570.689189, bitrate: 10160 kb/s
  Program 1007
    Metadata:
      service_name    : bTV
      service_provider: BULSATCOM
    Stream #0.0[0x50]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR 16:15 DAR 4:3], 10000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x51](bul): Audio: mp2, 48000 Hz, stereo, s16, 160 kb/s
Output #0, vob, to 'file.mpg':
  Metadata:
    encoder         : Lavf53.14.0
    Stream #0.0: Video: mpeg2video, yuv420p, 720x576 [PAR 16:15 DAR 4:3], q=2-31, 10000 kb/s, 90k tbn, 25 tbc
    Stream #0.1(bul): Audio: mp2, 48000 Hz, stereo, 160 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press ctrl-c to stop encoding
frame= 1526 fps=  0 q=-1.0 Lsize=   18630kB time=60.67 bitrate=2515.4kbits/s
video:17211kB audio:1185kB global headers:0kB muxing overhead 1.273521%

mediainfo file.mpg

General
Complete name                            : file.mpg
Format                                   : MPEG-PS
File size                                : 18.2 MiB
Duration                                 : 1mn 1s
Overall bit rate mode                    : Variable
Overall bit rate                         : 2 502 Kbps

Video
ID                                       : 224 (0xE0)
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : Main@Main
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Custom
Format settings, GOP                     : M=3, N=12
Duration                                 : 1mn 1s
Bit rate mode                            : Variable
Bit rate                                 : 2 292 Kbps
Maximum bit rate                         : 10 000 Kbps
Width                                    : 720 pixels
Height                                   : 576 pixels
Display aspect ratio                     : 4:3
Frame rate                               : 25.000 fps
Standard                                 : PAL
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                               : Top Field First
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.221
Stream size                              : 16.7 MiB (92%)

Audio
ID                                       : 192 (0xC0)
Format                                   : MPEG Audio
Format version                           : Version 1
Format profile                           : Layer 2
Duration                                 : 1mn 0s
Bit rate mode                            : Constant
Bit rate                                 : 160 Kbps
Channel(s)                               : 2 channels
Sampling rate                            : 48.0 KHz
Compression mode                         : Lossy
Delay relative to video                  : -146ms
Stream size                              : 1.16 MiB (6%)