GStreamer for Tiny Devices Olivier Crte Open First Who am I ? - PowerPoint PPT Presentation

GStreamer for Tiny Devices Olivier Crête Open First

Who am I ? ● GStreamer at Collabora since 2007 ● Started with VVoIP: Telepathy & Farstream ● Helps our customers use GStreamer – Many embedded projects 2

A Tiny Device? ● Flash Storage ● Slow CPU ● Little RAM 3

Overview of GStreamer 4

Pipelines! 5

GStreamer in Applications 6

Pipelines! 7

GStreamer: Perfect for embedded! ● Complete Zero-Copy toolkit – Full negotiation – Buffer lifetime – Synchronization ● Loads and loads of hardware enabled plugins ● Very fast prototyping 8

Example: A Security Camera ● 16 MB Flash ● 1 GB RAM ● RTSP Server ● ARMv7 9

Example: A RTSP to MP4 file segments ● Captures 2s clips from RTSP server rtspsrc rtph264depay h264parse splitmuxsink 10

Example: A RTSP to MP4 file segments ● Prototype on PC: g s t - l a u n c h - 1 . 0 r t s p s r c l o c a t i o n = r t s p : / / . . . ! r t p h 2 6 4 d e p a y ! h 2 6 4 p a r s e ! s p l i t m u x s i n k l o c a t i o n = f i l e _ t e m p l a t e _ % 0 5 d . m p 4 11

Version 0: A shell script with gst-launch-1.0 ● Complete GStreamer build – 287 MB for total build – 82 MB of dynamic libraries 287 MB 12

Version 0.1: A shell script with gst-launch-1.0 ● Strip it – 17 MB of dynamic libraries 17 MB 13

Version 1: A C program # i n c l u d e < g s t / g s t . h > # i n c l u d e < u n i s t d . h > i n t m a i n ( i n t a r g c , c h a r * * a r g v ) { G s t E l e m e n t * p i p e l i n e ; G E r r o r * e r r o r = N U L L ; g s t _ i n i t ( & a r g c , & a r g v ) ; p i p e l i n e = g s t _ p a r s e _ l a u n c h ( " r t s p s r c l o c a t i o n = r t s p : / / 1 2 7 . 0 . 0 . 1 : 8 5 5 4 / t e s t ! r t p h 2 6 4 d e p a y ! h 2 6 4 p a r s e ! s p l i t m u x s i n k m a x - s i z e - t i m e = 2 l o c a t i o n = v i d e o % 0 5 d . m p 4 " , & e r r o r ) ; i f ( ! p i p e l i n e ) g _ e r r o r ( " E r r o r : % s " , e r r o r - > m e s s a g e ) ; g s t _ e l e m e n t _ s e t _ s t a t e ( p i p e l i n e , G S T _ S T A T E _ P L A Y I N G ) ; p a u s e ( ) ; g s t _ e l e m e n t _ s e t _ s t a t e ( p i p e l i n e , G S T _ S T A T E _ N U L L ) ; r e t u r n 0 ; } 14

Version 1: A C program (Makefile) S Y S R O O T = / h o m e / o c r e t e / c o l l a b o r a / c e r b e r o / t o o l c h a i n / s y s r o o t - g l i b c - l i n a r o - 2 . 2 5 - 2 0 1 7 . 0 8 - a r m - l i n u x - g n u e a b i h f C C = / h o m e / o c r e t e / c o l l a b o r a / c e r b e r o / t o o l c h a i n / g c c - l i n a r o - 7 . 1 . 1 - 2 0 1 7 . 0 8 - i 6 8 6 _ a r m - l i n u x - g n u e a b i h f / b i n / a r m - l i n u x - g n u e a b i h f - g c c P K G _ C O N F I G _ P A T H = / h o m e / o c r e t e / c o l l a b o r a / c e r b e r o / b u i l d / d i s t / l i n u x _ a r m v 7 / l i b / p k g c o n f i g p r o g r a m : p r o g r a m . c M a k e f i l e l i b t o o l l i n k - - t a g = C C $ ( C C ) ` P K G _ C O N F I G _ P A T H = $ ( P K G _ C O N F I G _ P A T H ) p k g - c o n f i g - - l i b s - - c f l a g s g s t r e a m e r - 1 . 0 ` p r o g r a m . c - o p r o g r a m 15

Version 1: A C program ● Binary: 13K – Stripped: 5.5K ● Plus 17 MB in libraries ● Total: 17 MB 17 MB 16

Static Build? ● Using libtool – l i b t o o l - s t a t i c - l i b t o o l - l i b s – p k g - c o n f i g – - s t a t i c ● 7.5 MB binary 1.5 MB ● Stripped: 1.5 MB static binary 17

Try on device ● Put on Flash, run it: * * ( p r o g r a m : 1 4 8 0 6 ) : E R R O R * * : E r r o r : n o e l e m e n t " r t s p s r c " ● Missing all the plugins! 18

Copy plugins ● All ? 17MB … . ● Only relevant?! – G S T _ D E B U G = G S T _ P L U G I N _ L O A D I N G : 4 ● Total 1.7 MB in plugins once stripped 1.7 MB 19

Try on device again ( p r o g r a m : 2 3 2 1 1 ) : G S t r e a m e r - W A R N I N G * * : F a i l e d t o l o a d p l u g i n ' / l i b / g s t r e a m e r - 1 . 0 / l i b g s t u d p . s o ' : l i b g s t n e t - 1 . 0 . s o . 0 : c a n n o t o p e n s h a r e d o b j e c t f i l e : N o s u c h f i l e o r d i r e c t o r y ● Plugins are not static! – Need to re-add libraries 17 MB – Back to 17 MB 20

Statically build plugins ● Declare functions like G S T _ P L U G I N _ S T A T I C _ D E C L A R E ( c o r e e l e m e n t s ) ; ● Register plugins – After g s t _ i n i t ( ) – G S T _ P L U G I N _ S T A T I C _ R E G I S T E R ( c o r e e l e m e n t s ) ; 21

Statically build plugins ● Link with - L / h o m e / o c r e t e / c o l l a b o r a / c e r b e r o / b u i l d / d i s t / l i n u x _ a r m v 7 / l i b / g s t r e a m e r - 1 . 0 - l g s t c o r e e l e m e n t s - l g s t i s o m p 4 - l g s t v i d e o p a r s e r s b a d - l g s t r t p - l g s t r t s p - l g s t r t p m a n a g e r - l g s t u d p 22

Statically build plugins ● Real static binary is 28 MB ● Stripped to 4.7 MB ● Really working on device 4.7 MB 23

Ask the compiler for HELLPPP ! ● Compile with -Os ● Disappointing, it hasn't improved! – Stripped Binary: 4.7 MB 4.7 MB 24

Strip functions that are not used ● Build with: - f f u n c t i o n - s e c t i o n s - f d a t a - s e c t i o n s ● Link with: - W l , - - g c - s e c t i o n s ● Stripped Binary : 4 MB 4 MB 25

Dig into! ● Find which .o files contribute to the sink ● Used – objdump – Python script ● Tool: Bloaty McBloatface – Did not work for me 26

Butcher GLib ● GLib has internal plugins ● Always registered ● Not used, but bot garbage collected ● Butcher them out 27

Butcher GLib ● Removed – GSettings – GDBus – AppInfo – Gapplication – Notifications https://people.collabora.com/~tester/Butcher-glib-remove-gdbus-gapplication-desktopap.patch 28

Butcher GLib ● Stripped binary down to 3.8 MB 3.8 MB 29

Cheating time: Compressed binary ● Using upx u p x - - b e s t p r o g r a m ● Compress down to 2 MB 2 MB 30

More steps ● Remove UTF-8 tables in GLib ● Dig into exact linked code 31

Thank you!