On 06/25/2012 02:42 PM, Mans Rullgard wrote:
Module: libav
Branch: master
Commit: 82992604706144910f4a2f875d48cfc66c1b70d7

Author:    Mans Rullgard <[email protected]>
Committer: Mans Rullgard <[email protected]>
Date:      Sat Jun 23 19:08:11 2012 +0100

x86: fft: convert sse inline asm to yasm

---

  libavcodec/x86/Makefile    |    1 -
  libavcodec/x86/fft_mmx.asm |  139 ++++++++++++++++++++++++++++++++++++++++---
  libavcodec/x86/fft_sse.c   |  110 ----------------------------------
  3 files changed, 129 insertions(+), 121 deletions(-)


Hi,

This commit is causing some strange interaction with libx264 in HandBrake under certain conditions. x264 is encoding at about 1/10th it's normal rate after updating to this commit.

A little more background. When doing ac3 passthru HandBrake encodes a single packet of silence data to ac3 that is uses for filling any gaps that it detects in the audio. Encoding of this packet happens before any other encoding or decoding starts. For some crazy reason, if we encode this silence, we get the x264 slowdown. If we do not encode the silence, the speed is ok. I ran gprof on the code to see where all the time is being spent and it is all in x264. So it's not like there is some run-away loop somewhere that is bringing everything to it's knees. I'm guessing some cpu state must not be getting cleared or restored properly somewhere.

John

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