BackEnd

Implemented by : Hastur, Cyclops

Back end

• Record and playback on DVB-T
• DVB-T (Freeview)
• Simultaneous record and playback
• Media sharing

---

Hardware

Back-end

• Dual TV and DVB-T tuner card(s)
• Storage Server connection

---

Operating Systems

• Debian
• OpenSolaris
• Nexenta - Ubuntu/Solaris

---

Data Partitioning

• Separate metadata and library trees allows some clients to collect metadata

Single Volume

• Each MEDIATYPE has separate library and metadata trees
• Data trees are grouped for export using "bind" mounts
• Matches nfs export concept

Logical Volumes Option

• Each MEDIATYPE has a logical volume, lv-MEDIATYPE
• Each lv-MEDIATYPE has separate library and metadata trees
• Trees are grouped for export using normal mounts
• Requires a resizeable filesystem (i.e. not XFS)

File Permissions

• Requires ACLs?

Users

| media-centre | Default owner | rw all media | ||

Groups

Group	Role	Permissions
mc-music	Plays music	ro music lib
mc-videos	Plays videos	ro video lib
mc-movies	Plays movies	ro movies lib
mc-photos	Shows photos	ro photos lib
mc-tv	Plays recordings	ro recordings
mc-games	Plays games	ro game roms lib
mcadm-music	Manages music	rw music library
mcadm-videos	Manages videos	rw video library
mcadm-movies	Manages movies	rw movie library
mcadm-photos	Manages photos	rw photo library
mcadm-tv	Manages recordings	rw recordings
mcadm-games	Manages games	rw game roms lib

• All media files have owner permissions "rwx"
• All media files have group (ACL mask) permissions "rwx"
• All media files have other permissions "---|"
• All MEDIATYPE files have named group "mcadm-MEDIATYPE" permissions "rw-"
• All MEDIATYPE files have named group "mc-MEDIATYPE" permissions "r--"
• All MEDIATYPE directories have default ACLs? reflecting the above permissions

Example Configuration

/etc/passwd

media-centre3000:3000:Media Centre:/nonexistent:/usr/sbin/nologin

Example /etc/group

mc-movies3003:mythtv,mediatomb,admin1,user1
mc-music3001:mythtv,mediatomb,mpd,admin1,user1
mc-photos3007:mythtv,admin1,user1
mc-tv3009:mythtv,mediatomb,admin1,user1
mc-videos3002:mediatomb,admin1,user1
mcadm-movies3006:,admin1
mcadm-music3004:mpd,admin1
mcadm-photos3008:,admin1
mcadm-tv3010:,admin1
mcadm-videos3005:,admin1
mc-users3011:admin1,user1

Example ACL (getfacl /mnt/media/movies)

# file: library
# owner: media-centre
# group: mcadm-movies
user::rwx
group::---
group:mc-movies:r-x
group:mcadm-movies:rwx
mask::rwx
other::---
default:user::rwx
default:group::r-x
default:group:mc-movies:r-x
default:group:mcadm-movies:rwx
default:rwx
default:other::---

User Contributed Files

• All users have a $user/shared-media directory with write permission
• $user/shared-media ACLs? allow access by mediasys groups
• mediasys/users/$user is a symlink to $user/shared-media
• CIFS requires wide links = yes for the mediasys share.
• Not compatible with NFS.

Data Export

• A single shared tree for mediasys
• Each MEDIATYPE library and metadata directory is mapped into the single tree.
• Shares per MEDIATYPE writeable by the admin group for that MEDIATYPE.

Example fstab

/etc/fstab

# Media mounts
/dev/vg-media/home        /home   ext4    defaults,noatime,nosuid,noauto,acl      0       0
/dev/vg-media/media       /mnt/media  ext4    defaults,noatime,nosuid,noauto,acl      0       0
# Export mounts
/mnt/media/movies/library /export/mediasys/movies/library none bind,noauto    0       0
/mnt/media/movies/metadata /export/mediasys/movies/meta none bind,noauto      0       0
/mnt/media/music/library /export/mediasys/music/library none bind,noauto      0       0
/mnt/media/music/metadata /export/mediasys/music/meta none bind,noauto        0       0
/mnt/media/tvshows/library /export/mediasys/tvshows/library none bind,noauto  0       0
/mnt/media/tvshows/metadata /export/mediasys/tvshows/meta none bind,noauto    0       0
/mnt/media/recordings /export/mediasys/recordings none bind,noauto    0       0
/mnt/media/photos/library /export/mediasys/photos/library none bind,noauto    0       0
/mnt/media/photos/metadata /export/mediasys/photos/meta none bind,noauto      0       0

Samba/CIFS

• Requires username/password

Example Configuration

/etc/smb.conf

[mediasys]
   path=/export/mediasys
   browseable = yes
   writable = yes
   mangled names = no
   follow symlinks = yes # for per-user shared-media
   wide links = yes  # for per-user shared-media
   valid users = mythtv,@mc-users

[homes]
   path=/home/%S
   comment = Home Directories
   browseable = no
   writable = yes
   create mask = 0700
   directory mask = 0700
   valid users = %S
   mangled names = no

# Administrative shares - not browseable by default
[movies]
   path=/mnt/media/movies
   browseable = no
   writable = yes
   mangled names = no
   valid users = @mcadm-movies

...

NFS

Read-only Exports (without security)

/etc/exports

/export/mediasys  192.168.0.0/24(ro,fsid=0,sync,no_subtree_check)
/export/mediasys/movies/library   192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/movies/meta      192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/tvshows/library  192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/tvshows/meta     192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/music/library    192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/music/meta       192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/photos/library   192.168.0.0/24(ro,nohide,sync,no_subtree_check)
/export/mediasys/photos/meta      192.168.0.0/24(ro,nohide,sync,no_subtree_check)

Permissions fixes for NFSv3?

/export/mediasys 192.168.0.0/24(ro,fsid=0,sync,no_subtree_check,all_squash,anongid=3000)
/export/mediasys/movies/library 192.168.0.0/24(ro,nohide,sync,no_subtree_check,anongid=3003)
...

mount -t nfs4 -o ro media: /mnt/media

$[Get Code]9

---

Capture Cards

Linux Chipset Support

ivtv Driver supported hardware

• CX23415?
• CX23416?

DVB-T

• http://www.linuxtv.org/wiki/index.php/DVB-T_PCI_Cards
• http://www.linuxtv.org/wiki/index.php/DVB-T_PCIe_Cards

| Card | HD | SD tuners | DVB-T tuners | Price | Notes | || | Nova-T-PCI | Yes | | 1 | £28 Ebuyer | Supported | | Nova-T-500 | Yes | | 2 | £55 Ebuyer | USB bridge device; not fully supported | | Pinnacle PCTV DVB-T Pro PCI | No | | 2 | £56 scan | No support | | DViCO FusionHDTV Dual Digital | Yes | | 2 |   |   | | AverTV? DVB-T A771 |   |   |   | £35 SpecialTech |   | | AverTV? DVB-T A777 | Yes | | 1 | Supplier?? | Replaces A771 | | TerraTec? Cinergy 2400i PCI-E |   | | 2 |   | No support yet | | Compro VideoMate? DVB-T200 PCI | Yes | | 1 |   |   |

---

CAMs?

• http://www.divineo.co.uk/cgi-bin/div-uk/elv-phoenix.html (can use for Nova-T PCI)

---

DVD Encoding

• http://lipas.uwasa.fi/~f76998/video/conversion/
• Test Videos

Profiles

High Quality Compressed

• H.264 video
• AC3? audio
• mp4 container
• ~2GB

High Quality Raw

• MPEG2?
• AC3? audio
• VOB
• ~9GB

---

Notes

• Hardware or software encoding?
  • Hard enc more expensive, Soft enc needs more powerful CPU
    • No encoder needed, DVB-T is MPEG2?. MPEG2?->MPEG4? needed anyway
• Does a software encoder require encoding to MPEG2??
  • Yes, or some other codec
• Can a software encoder encode to something else in Realtime?
  • DivX?, Xvid, H.264 check processor requirements
• MPEG-4 encoders
  • Hauppauge HVR-4000 does H.264
• Front end may need up to 1GB RAM to store MythTV? UI elements for 1080p displays
• VIA UniChromePro? graphics may eventually be capable of H.264 acceleration with XvMC?
• VIA & nVidia cards can accelerate decoding of MPEG2?