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8a129077cc
AV_CODEC_CAP_AUTO_THREADS was originally added in b4d44a45f9 to mark
codecs that spawn threads internally and are able to select an optimal
threads count by themselves (all such codecs are wrappers around
external libraries). It is used by lavc generic code to check whether it
should handle thread_count=0 itself or pass the zero directly to the
codec implementation. Within this meaning, it is clearly supposed to be
an internal cap rather than a public one, since from the viewpoint of a
libavcodec user, lavc ALWAYS handles thread_count=0. Whether it happens
in the generic code or within the codec internals is not a meaningful
difference for the caller.
External aspects of this flag will be dealt with in the following
commit.
89 lines
3.1 KiB
C
89 lines
3.1 KiB
C
/*
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* Copyright (c) 2004 Roman Shaposhnik
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* Copyright (c) 2008 Alexander Strange (astrange@ithinksw.com)
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*
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* Many thanks to Steven M. Schultz for providing clever ideas and
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* to Michael Niedermayer <michaelni@gmx.at> for writing initial
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* implementation.
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Multithreading support functions
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* @see doc/multithreading.txt
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*/
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#include "avcodec.h"
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#include "internal.h"
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#include "pthread_internal.h"
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#include "thread.h"
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/**
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* Set the threading algorithms used.
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*
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* Threading requires more than one thread.
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* Frame threading requires entire frames to be passed to the codec,
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* and introduces extra decoding delay, so is incompatible with low_delay.
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*
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* @param avctx The context.
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*/
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static void validate_thread_parameters(AVCodecContext *avctx)
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{
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int frame_threading_supported = (avctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS)
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&& !(avctx->flags & AV_CODEC_FLAG_TRUNCATED)
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&& !(avctx->flags & AV_CODEC_FLAG_LOW_DELAY)
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&& !(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS);
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if (avctx->thread_count == 1) {
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avctx->active_thread_type = 0;
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} else if (frame_threading_supported && (avctx->thread_type & FF_THREAD_FRAME)) {
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avctx->active_thread_type = FF_THREAD_FRAME;
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} else if (avctx->codec->capabilities & AV_CODEC_CAP_SLICE_THREADS &&
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avctx->thread_type & FF_THREAD_SLICE) {
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avctx->active_thread_type = FF_THREAD_SLICE;
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} else if (!(avctx->codec->caps_internal & FF_CODEC_CAP_AUTO_THREADS)) {
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avctx->thread_count = 1;
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avctx->active_thread_type = 0;
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}
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if (avctx->thread_count > MAX_AUTO_THREADS)
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av_log(avctx, AV_LOG_WARNING,
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"Application has requested %d threads. Using a thread count greater than %d is not recommended.\n",
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avctx->thread_count, MAX_AUTO_THREADS);
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}
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int ff_thread_init(AVCodecContext *avctx)
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{
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validate_thread_parameters(avctx);
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if (avctx->active_thread_type&FF_THREAD_SLICE)
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return ff_slice_thread_init(avctx);
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else if (avctx->active_thread_type&FF_THREAD_FRAME)
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return ff_frame_thread_init(avctx);
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return 0;
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}
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void ff_thread_free(AVCodecContext *avctx)
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{
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if (avctx->active_thread_type&FF_THREAD_FRAME)
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ff_frame_thread_free(avctx, avctx->thread_count);
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else
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ff_slice_thread_free(avctx);
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}
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