Recently I got some inquiries about h264 and altivec. just testing decode time was disappointing to some user.<\/p>\n
I did my test and on my g4 1.6 I got about the double ofthe speed he experienced on his g5 2.4.<\/p>\n
time nice –20 .\/ffmpeg -i ~ryan\/bluesky_HD_CAVLC_JM93_217f.264 -f \trawvideo – > \/dev\/null
\nreal 0m47.685s
\nuser 0m44.304s
\nsys 0m3.220s<\/p>\n
cat \/proc\/cpuinfo
\nprocessor : 0
\ncpu : ppc970, altivec supported
\nclock : 2400.000000MHz
\nrevision : 4.0 (pvr 0070 0400)<\/p>\n
time nice –20 .\/ffmpeg -i \/tmp\/bluesky_HD_CAVLC_JM93_217f.264 -f
\nrawvideo – > \/dev\/null
\nreal 0m25.877s
\nuser 0m23.768s
\nsys 0m1.904s<\/p>\n
cat \/proc\/cpuinfo
\nprocessor : 0
\ncpu : 7447A, altivec supported
\nclock : 1666.666000MHz
\nrevision : 0.5 (pvr 8003 0105)<\/p>\n
The ffmpeg code is the same, I hadn’t use anything but the stock cflags, same for him.
\nI was expecting quite a different result, time hunt the slow gear!<\/p>\n
I used oprofile<\/p>\n
just started and stopped it befor the ffmpeg call, and the asked opreport to compute some statistics about symbols.<\/p>\n
an excerpt<\/p>\n
CPU: PowerPC G4, speed 1666.67 MHz (estimated)
\nCounted CYCLES events (Cycles) with a unit mask of 0x00 (No unit mask) count 100000
\nsamples % image name symbol name
\n60355 23.2602 libc-2.4.so _wordcopy_fwd_aligned
\n13572 5.2305 ffmpeg_g put_h264_chroma_mc8_altivec
\n13417 5.1708 ffmpeg_g filter_mb
\n11379 4.3853 ffmpeg_g put_h264_qpel16_h_lowpass_altivec
\n9700 3.7383 ffmpeg_g fill_caches
\n9332 3.5965 ffmpeg_g hl_decode_mb
\n8201 3.1606 vmlinux __flush_dcache_icache<\/p>\n
Looks like I’ll have to replace something… or start thinking about optimized glibc…
\n(mine is built targeting my cpu and is pretty recent, I wonder if the G5 isn’t running on an older or generic built glibc…)<\/p>\n","protected":false},"excerpt":{"rendered":"
Recently I got some inquiries about h264 and altivec. just testing decode time was disappointing to some user. I did my test and on my g4 1.6 I got about the double ofthe speed he experienced on his g5 2.4. time nice –20 .\/ffmpeg -i ~ryan\/bluesky_HD_CAVLC_JM93_217f.264 -f rawvideo – > \/dev\/null real 0m47.685s user 0m44.304s … Continue reading oprofiling ffh264<\/span><\/a><\/p>\n","protected":false},"author":10,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true},"categories":[11,14,6,5],"tags":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p1aGWH-1q","_links":{"self":[{"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/posts\/88"}],"collection":[{"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/users\/10"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/comments?post=88"}],"version-history":[{"count":0,"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/posts\/88\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/media?parent=88"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/categories?post=88"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.gentoo.org\/lu_zero\/wp-json\/wp\/v2\/tags?post=88"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}