doc/multithreading.txt File Reference

Typedefs
using	clients = =============================================Slice threading-*The client's draw_horiz_band() must be thread-safe according to the comment in avcodec.h.Frame threading-*Restrictions with slice threading also apply.*For best performance, the client should set thread_safe_callbacks if it provides a thread-safe get_buffer() callback.*There is one frame of delay added for every thread beyond the first one.Clients must be able to handle this

Functions
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before	ff_thread_await_progress () has been called on them.reget_buffer() and buffer age optimizations no longer work.*The contents of buffers must not be written to after ff_thread_report_progress() has been called on them.This includes draw_edges().Porting codecs to frame threading
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling	get_buffer ()
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling up to before the decode process starts Call	ff_thread_finish_setup () afterwards.If some code can't be moved
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have	update_thread_context () run it in the next thread.If the codec allocates writable tables in its init()
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an	init_thread_copy () which re-allocates them for other threads.Add AV_CODEC_CAP_FRAME_THREADS to the codec capabilities.There will be very little speed gain at this point but it should work.If there are inter-frame dependencies
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an so the codec calls ff_thread_report	await_progress ()
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an so the codec calls ff_thread_report set AVCodecInternal allocate_progress The frames must then be freed with	ff_thread_release_buffer ().Otherwise leave it at zero and decode directly into the user-supplied frames.Call ff_thread_report_progress() after some part of the current picture has decoded.A good place to put this is where draw_horiz_band() is called-add this if it isn't called anywhere
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel *The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an so the codec calls ff_thread_report set AVCodecInternal allocate_progress The frames must then be freed with as it s useful too and the implementation is trivial when you re doing this Note that	draw_edges () needs to be called before reporting progress.Before accessing a reference frame or its MVs

Variables
FFmpeg multithreading	methods
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec	implementations
the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across	frames

Typedef Documentation

using clients = ============================================= Slice threading - * The client's draw_horiz_band() must be thread-safe according to the comment in avcodec.h. Frame threading - * Restrictions with slice threading also apply. * For best performance, the client should set thread_safe_callbacks if it provides a thread-safe get_buffer() callback. * There is one frame of delay added for every thread beyond the first one. Clients must be able to handle this

Definition at line 26 of file multithreading.txt.

Function Documentation

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before ff_thread_await_progress

(

)

Referenced by await_reference_mb_row(), await_reference_row(), await_references(), decode(), decode_frame(), decode_mb_row_no_filter(), decode_mode(), decode_slice(), ff_er_frame_end(), find_ref_mvs(), guess_mv(), h264_field_start(), handle_p_frame_apng(), handle_p_frame_png(), hevc_await_progress(), is_intra_more_likely(), mc_chroma_scaled(), mc_chroma_unscaled(), mc_luma_scaled(), mc_luma_unscaled(), mpeg4_decode_mb(), mpv_reconstruct_mb_internal(), rv34_decode_mv(), rv34_mc(), temporal_luma_motion_vector(), vp78_decode_frame(), vp8_mc_chroma(), and vp8_mc_luma().

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling get_buffer

(

)

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling up to before the decode process starts Call ff_thread_finish_setup

(

)

Referenced by decode_frame(), decode_idat_chunk(), decode_nal_units(), ff_h263_decode_frame(), ff_rv34_decode_frame(), hap_decode(), hevc_frame_start(), mimic_decode_frame(), mpeg_field_start(), tak_decode_frame(), vp3_decode_frame(), vp78_decode_frame(), and vp9_decode_frame().

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have update_thread_context

(

)

Referenced by copy_fields(), decode_frame_common(), png_dec_end(), and tak_decode_frame().

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an init_thread_copy

(

)

Referenced by alac_decode_init(), decode_end(), decode_frame(), decode_init(), ff_vp8_decode_init(), flac_decode_frame(), png_dec_end(), read_huffman_tree(), tak_decode_frame(), and wv_alloc_frame_context().

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an so the codec calls ff_thread_report await_progress

(

)

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an so the codec calls ff_thread_report set AVCodecInternal allocate_progress The frames must then be freed with ff_thread_release_buffer

(

)

Referenced by copy_fields(), decode_frame(), decode_frame_common(), decode_idat_chunk(), ff_ffv1_close(), ff_h264_unref_picture(), ff_hevc_unref_frame(), ff_mpeg_unref_picture(), mimic_decode_end(), mimic_decode_frame(), mimic_decode_init(), png_dec_end(), update_frames(), vp3_decode_flush(), vp3_decode_frame(), vp8_alloc_frame(), vp8_release_frame(), vp9_decode_flush(), vp9_decode_frame(), vp9_decode_free(), vp9_decode_init(), and vp9_frame_unref().

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across will not work because their bitstreams cannot be decoded in parallel* The contents of buffers must not be read before as well as code calling up to before the decode process starts Call have add an so the codec calls ff_thread_report set AVCodecInternal allocate_progress The frames must then be freed with as it s useful too and the implementation is trivial when you re doing this Note that draw_edges

(

)

Variable Documentation

FFmpeg multithreading methods

Initial value:

==============================================

FFmpeg provides two methods for multithreading codecs.

Slice threading decodes multiple parts of a frame at the same time

Definition at line 2 of file multithreading.txt.

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec implementations

Initial value:

==============================================

Slice threading -
 None except that there must be something worth executing in parallel.

Frame threading -
* Codecs can only accept entire pictures per packet.
* Codecs similar to ffv1

Definition at line 30 of file multithreading.txt.

the pkt_dts and pkt_pts fields in AVFrame will work as usual Restrictions on codec whose streams don t reset across frames

Definition at line 30 of file multithreading.txt.