@ -448,6 +448,8 @@ def ffmpeg_cut_segment(segment, cut_start=None, cut_end=None):
taking care to preserve stream order and other metadata .
Used when doing a fast cut .
"""
logging . debug ( f " Will cut segment for range ( { cut_start } , { cut_end } ): { segment . path } " )
args = [ ]
# output from ffprobe is generally already sorted but let's be paranoid,
# because the order of map args matters.
@ -593,30 +595,177 @@ def rough_cut_segments(segment_ranges, ranges):
This method works by simply concatenating all the segments , without any re - encoding .
"""
for segments in segment_ranges :
for segment in segments :
if segment is None :
continue
with open ( segment . path , ' rb ' ) as f :
for chunk in read_chunks ( f ) :
yield chunk
yield from read_segments ( segments )
@timed ( ' cut ' , cut_type = ' fast ' , normalize = lambda ret , sr , ranges : range_total ( ranges ) )
def fast_cut_segments ( segment_ranges , ranges :
def fast_cut_segments ( segment_ranges , ranges , transitions , smart = False ) :
""" Yields chunks of a MPEGTS video file covering the exact timestamp ranges.
segments should be a list of segment lists as returned by get_best_segments ( ) for each range .
This method works by only cutting the first and last segments of each range ,
and concatenating everything together . Ranges are cut between with no transitions .
This method works by only cutting the first and last segments of each range
( or more if there are longer transitions ) , and concatenating everything together .
This only works if the same codec settings etc are used across all segments .
This should almost always be true but may cause weird results if not .
"""
if len ( segment_ranges ) != len ( ranges ) :
raise ValueError ( " You need to provide one segment list for each range " )
for segments , ( start , end ) in zip ( segment_ranges , ranges ) :
# We could potentially optimize here by cutting all firsts/lasts in parallel
# instead of doing them in order, but that's probably not that helpful and would
# greatly complicate things.
yield from fast_cut_range ( segments , start , end )
if not ( len ( segment_ranges ) == len ( ranges ) == len ( transitions ) + 1 ) :
raise ValueError ( " Cut input length mismatch: {} segment ranges, {} time ranges, {} transitions " . format (
len ( segment_ranges ) ,
len ( ranges ) ,
len ( transitions ) ,
) )
# We subdivide each range into a start, middle and end.
# The start covers any incoming transition + a partial first segment.
# The end covers any outgoing transition + a partial last segment.
# The middle is everything else, split on any discontinuities.
# Furthermore, one range's start may be cut together with the previous range's end
# if there is a transition.
# We collect iterators covering all of these sections into a single ordered list.
parts = [ ]
# In each iteration we handle:
# - The transition, including previous range's end + this range's start, if there is one
# - Otherwise, we handle this range's start but assume previous range's end is already done
# - This range's middle
# - This range's end, unless it's part of the next transition.
# We pass the previous range's end segments and offset to the next iteration via prev_end
prev_end = None # None | (segments, offset)
for segments , ( start , end ) , in_transition , out_transition in zip (
segment_ranges ,
ranges ,
# pad transitions with an implicit "hard cut" before and after the actual ranges.
[ None ] + transitions ,
transitions + [ None ] ,
) :
# prev_end should be set if and only if there is an in transition
assert ( in_transition is None ) == ( prev_end is None )
# Determine start and end cut points, unless we start/end with a discontinuity
cut_start = None
cut_end = None
if segments [ 0 ] is not None :
cut_start = ( start - segments [ 0 ] . start ) . total_seconds ( )
if cut_start < 0 :
raise ValueError ( " First segment doesn ' t begin until after cut start, but no leading hole indicated " )
if segments [ - 1 ] is not None :
cut_end = ( end - segments [ - 1 ] . start ) . total_seconds ( )
if cut_end < 0 :
raise ValueError ( " Last segment ends before cut end, but no trailing hole indicated " )
# Handle start
start_cut_end = None
if in_transition is not None :
video_type , duration = in_transition
# Get start segments, and split them from the full range of segments
# by finding the first segment that starts after the transition ends
transition_end = start + datetime . timedelta ( seconds = duration )
for i , segment in enumerate ( segments ) :
if segment is not None and segment . start > transition_end :
start_segments = segments [ : i ]
segments = segments [ i : ]
break
else :
# Unlikely,but in this case the start transition is the entire range
# and we should include the end cut.
start_segments = segments
segments = [ ]
start_cut_end = cut_end
cut_end = None
if len ( start_segments ) == 0 :
raise ValueError ( f " Could not find any video data for { duration } s transition into range ( { start } , { end } ) " )
raise NotImplementedError ( " no transitions yet " )
# TODO append ffmpeg with transition, start_segments, prev_end, cut_start, start_cut_end
elif cut_start is not None and cut_start > 0 :
# Cut start segment, unless it is a discontinuity or doesn't need cutting
segment = segments [ 0 ]
segments = segments [ 1 : ]
if not segments :
# The whole thing is only one segment, so also apply end cut
start_cut_end = cut_end
cut_end = None
ffmpeg = ffmpeg_cut_segment ( segment , cut_start , start_cut_end )
parts . append ( read_from_stdout ( ffmpeg ) )
else :
pass # No cutting required at start
prev_end = None
# Handle end, but don't append it to parts list just yet.
end_cut_part = None
if out_transition is not None :
video_type , duration = out_transition
# Get end segments, and split them from the full range of segments
# by finding the last segment that ends before the transition starts
transition_start = end - datetime . timedelta ( seconds = duration )
for i , segment in enumerate ( segments ) :
if segment is not None and segment . end > = transition_start :
end_segments = segments [ i : ]
segments = segments [ : i ]
else :
raise ValueError ( f " Could not find any video data for { duration } s transition out of range ( { start } , { end } ) that is not already part of another transition " )
# offset is how many seconds into end_segments the transition should start.
# We know that end_segments is not empty as otherwise we would have hit the for/else condition.
# We also know that end_segments[0] is not None as it is one of our conditions for picking it.
# It is however possible for end_segments[0] to start AFTER the transition should have started
# due to a hole immediately before. Technically a negative offset is still correct in this case,
# and ideally would cause ffmpeg to treat the transition as "already in progress" when we start.
# I haven't tested this behaviour but the alternative is to just fail so it's worth a shot.
offset = ( transition_start - end_segments [ 0 ] . start ) . total_seconds ( )
prev_end = end_segments , offset
elif cut_end is not None :
# Cut end segment, unless it is a discontinuity, doesn't need cutting, or was already
# cut as part of start (which sets cut_end to None).
assert segments # Either we should still have segments left, or the start cut should have included the end
segment = segments [ - 1 ]
segments = segments [ : - 1 ]
ffmpeg = ffmpeg_cut_segment ( segment , cut_end = cut_end )
end_cut_part = read_from_stdout ( ffmpeg )
# For each remaining segment in the middle, append a part per run without a discontinuity
run = [ ]
for segment in segments :
if segment is None :
if run :
parts . append ( read_segments ( run ) )
run = [ ]
else :
run . append ( segment )
if run :
parts . append ( read_segments ( run ) )
if end_cut_part is not None :
parts . append ( end_cut_part )
# after all that, double check the last range had no transition and we carried nothing over
assert prev_end is None
# yield from each part in order, applying fixts if needed
fixts = FixTSSequence ( ) if smart else None
for part in parts :
for i , chunk in enumerate ( part ) :
# Since long smart cuts can be CPU and disk bound for quite a while,
# yield to give other things a chance to run. Note this will run on the first
# iteration so every part switch also introduces an idle yield.
if i % 1000 == 0 :
gevent . idle ( )
yield fixts . feed ( chunk ) if smart else chunk
if fixts :
fixts . next ( )
def read_from_stdout ( ffmpeg_context ) :
""" Takes a ffmpeg context manager as returned by ffmpeg_cut_many() and its wrapper functions,
and yields data chunks from ffmpeg ' s stdout. " " "
with ffmpeg_context as ffmpeg :
yield from read_chunks ( ffmpeg . stdout )
def read_segments ( segments ) :
""" Takes a list of segment files and yields data chunks from each one in order. Ignores holes. """
for segment in segments :
if segment is None :
continue
with open ( segment . path , ' rb ' ) as f :
yield from read_chunks ( f )
class FixTSSequence :
@ -640,85 +789,12 @@ class FixTSSequence:
@timed ( ' cut ' , cut_type = ' smart ' , normalize = lambda ret , sr , ranges : range_total ( ranges ) )
def smart_cut_segments ( segment_ranges , ranges :
def smart_cut_segments ( segment_ranges , ranges , transitions ):
"""
As per fast_cut_segments ( ) , except we also do a " fix " pass over the resulting video stream
to re - time internal timestamps to avoid discontinuities and make sure the video starts at t = 0.
"""
if len ( segment_ranges ) != len ( ranges ) :
raise ValueError ( " You need to provide one segment list for each range " )
fixts = FixTSSequence ( )
for segments , ( start , end ) in zip ( segment_ranges , ranges ) :
yield from fast_cut_range ( segments , start , end , fixts = fixts )
@timed ( ' cut_range ' , cut_type = ' fast ' , normalize = lambda _ , segments , start , end , * * k : ( end - start ) . total_seconds ( ) )
def fast_cut_range ( segments , start , end , fixts = None ) :
""" Does a fast cut for an individual range of segments.
If a FixTSSequence is given , fixes timestamps to avoid discontinuities
between cut segments and passed through segments .
"""
# how far into the first segment to begin (if no hole at start)
cut_start = None
if segments [ 0 ] is not None :
cut_start = ( start - segments [ 0 ] . start ) . total_seconds ( )
if cut_start < 0 :
raise ValueError ( " First segment doesn ' t begin until after cut start, but no leading hole indicated " )
# how far into the final segment to end (if no hole at end)
cut_end = None
if segments [ - 1 ] is not None :
cut_end = ( end - segments [ - 1 ] . start ) . total_seconds ( )
if cut_end < 0 :
raise ValueError ( " Last segment ends before cut end, but no trailing hole indicated " )
# Set first and last only if they actually need cutting.
# Note this handles both the cut_start = None (no first segment to cut)
# and cut_start = 0 (first segment already starts on time) cases.
first = segments [ 0 ] if cut_start else None
last = segments [ - 1 ] if cut_end else None
for i , segment in enumerate ( segments ) :
# Since long smart cuts can be CPU and disk bound for quite a while,
# yield to give other things a chance to run.
if i % 1000 == 0 :
gevent . idle ( )
if segment is None :
logging . debug ( " Skipping discontinuity while cutting " )
# TODO: If we want to be safe against the possibility of codecs changing,
# we should check the streams_info() after each discontinuity.
# To keep our output clean, we reset our FixTS so the output doesn't contain
# the discontinuity. The video just cuts to the next segment.
if fixts :
fixts . next ( )
continue
# note first and last might be the same segment.
# note a segment will only match if cutting actually needs to be done
# (ie. cut_start or cut_end is not 0)
if segment in ( first , last ) :
if fixts :
fixts . next ( )
with ffmpeg_cut_segment (
segment ,
cut_start if segment == first else None ,
cut_end if segment == last else None ,
) as ffmpeg :
for chunk in read_chunks ( ffmpeg . stdout ) :
yield fixts . feed ( chunk ) if fixts else chunk
if fixts :
fixts . next ( )
else :
# no cutting needed, just serve the file
with open ( segment . path , ' rb ' ) as f :
for chunk in read_chunks ( f ) :
yield fixts . feed ( chunk ) if fixts else chunk
if fixts :
# check for errors and indicate range is finished
fixts . next ( )
return fast_cut_segments ( segment_ranges , ranges , transitions , smart = True )
def feed_input ( segments , pipe ) :
Mike Lang
6 months ago
committed by
Mike Lang