bazarr/libs/ffmpeg/tests/test_ffmpeg.py

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from __future__ import unicode_literals
from builtins import bytes
from builtins import range
from builtins import str
import ffmpeg
import os
import pytest
import random
import re
import subprocess
try:
import mock # python 2
except ImportError:
from unittest import mock # python 3
TEST_DIR = os.path.dirname(__file__)
SAMPLE_DATA_DIR = os.path.join(TEST_DIR, 'sample_data')
TEST_INPUT_FILE1 = os.path.join(SAMPLE_DATA_DIR, 'in1.mp4')
TEST_OVERLAY_FILE = os.path.join(SAMPLE_DATA_DIR, 'overlay.png')
TEST_OUTPUT_FILE1 = os.path.join(SAMPLE_DATA_DIR, 'out1.mp4')
TEST_OUTPUT_FILE2 = os.path.join(SAMPLE_DATA_DIR, 'out2.mp4')
BOGUS_INPUT_FILE = os.path.join(SAMPLE_DATA_DIR, 'bogus')
subprocess.check_call(['ffmpeg', '-version'])
def test_escape_chars():
assert ffmpeg._utils.escape_chars('a:b', ':') == 'a\:b'
assert ffmpeg._utils.escape_chars('a\\:b', ':\\') == 'a\\\\\\:b'
assert (
ffmpeg._utils.escape_chars('a:b,c[d]e%{}f\'g\'h\\i', '\\\':,[]%')
== 'a\\:b\\,c\\[d\\]e\\%{}f\\\'g\\\'h\\\\i'
)
assert ffmpeg._utils.escape_chars(123, ':\\') == '123'
def test_fluent_equality():
base1 = ffmpeg.input('dummy1.mp4')
base2 = ffmpeg.input('dummy1.mp4')
base3 = ffmpeg.input('dummy2.mp4')
t1 = base1.trim(start_frame=10, end_frame=20)
t2 = base1.trim(start_frame=10, end_frame=20)
t3 = base1.trim(start_frame=10, end_frame=30)
t4 = base2.trim(start_frame=10, end_frame=20)
t5 = base3.trim(start_frame=10, end_frame=20)
assert t1 == t2
assert t1 != t3
assert t1 == t4
assert t1 != t5
def test_fluent_concat():
base = ffmpeg.input('dummy.mp4')
trimmed1 = base.trim(start_frame=10, end_frame=20)
trimmed2 = base.trim(start_frame=30, end_frame=40)
trimmed3 = base.trim(start_frame=50, end_frame=60)
concat1 = ffmpeg.concat(trimmed1, trimmed2, trimmed3)
concat2 = ffmpeg.concat(trimmed1, trimmed2, trimmed3)
concat3 = ffmpeg.concat(trimmed1, trimmed3, trimmed2)
assert concat1 == concat2
assert concat1 != concat3
def test_fluent_output():
ffmpeg.input('dummy.mp4').trim(start_frame=10, end_frame=20).output('dummy2.mp4')
def test_fluent_complex_filter():
in_file = ffmpeg.input('dummy.mp4')
return ffmpeg.concat(
in_file.trim(start_frame=10, end_frame=20),
in_file.trim(start_frame=30, end_frame=40),
in_file.trim(start_frame=50, end_frame=60),
).output('dummy2.mp4')
def test_node_repr():
in_file = ffmpeg.input('dummy.mp4')
trim1 = ffmpeg.trim(in_file, start_frame=10, end_frame=20)
trim2 = ffmpeg.trim(in_file, start_frame=30, end_frame=40)
trim3 = ffmpeg.trim(in_file, start_frame=50, end_frame=60)
concatted = ffmpeg.concat(trim1, trim2, trim3)
output = ffmpeg.output(concatted, 'dummy2.mp4')
assert repr(in_file.node) == 'input(filename={!r}) <{}>'.format(
'dummy.mp4', in_file.node.short_hash
)
assert repr(trim1.node) == 'trim(end_frame=20, start_frame=10) <{}>'.format(
trim1.node.short_hash
)
assert repr(trim2.node) == 'trim(end_frame=40, start_frame=30) <{}>'.format(
trim2.node.short_hash
)
assert repr(trim3.node) == 'trim(end_frame=60, start_frame=50) <{}>'.format(
trim3.node.short_hash
)
assert repr(concatted.node) == 'concat(n=3) <{}>'.format(concatted.node.short_hash)
assert repr(output.node) == 'output(filename={!r}) <{}>'.format(
'dummy2.mp4', output.node.short_hash
)
def test_stream_repr():
in_file = ffmpeg.input('dummy.mp4')
assert repr(in_file) == 'input(filename={!r})[None] <{}>'.format(
'dummy.mp4', in_file.node.short_hash
)
split0 = in_file.filter_multi_output('split')[0]
assert repr(split0) == 'split()[0] <{}>'.format(split0.node.short_hash)
dummy_out = in_file.filter_multi_output('dummy')['out']
assert repr(dummy_out) == 'dummy()[{!r}] <{}>'.format(
dummy_out.label, dummy_out.node.short_hash
)
def test__get_args__simple():
out_file = ffmpeg.input('dummy.mp4').output('dummy2.mp4')
assert out_file.get_args() == ['-i', 'dummy.mp4', 'dummy2.mp4']
def test_global_args():
out_file = (
ffmpeg.input('dummy.mp4')
.output('dummy2.mp4')
.global_args('-progress', 'someurl')
)
assert out_file.get_args() == [
'-i',
'dummy.mp4',
'dummy2.mp4',
'-progress',
'someurl',
]
def _get_simple_example():
return ffmpeg.input(TEST_INPUT_FILE1).output(TEST_OUTPUT_FILE1)
def _get_complex_filter_example():
split = ffmpeg.input(TEST_INPUT_FILE1).vflip().split()
split0 = split[0]
split1 = split[1]
overlay_file = ffmpeg.input(TEST_OVERLAY_FILE)
overlay_file = ffmpeg.crop(overlay_file, 10, 10, 158, 112)
return (
ffmpeg.concat(
split0.trim(start_frame=10, end_frame=20),
split1.trim(start_frame=30, end_frame=40),
)
.overlay(overlay_file.hflip())
.drawbox(50, 50, 120, 120, color='red', thickness=5)
.output(TEST_OUTPUT_FILE1)
.overwrite_output()
)
def test__get_args__complex_filter():
out = _get_complex_filter_example()
args = ffmpeg.get_args(out)
assert args == [
'-i',
TEST_INPUT_FILE1,
'-i',
TEST_OVERLAY_FILE,
'-filter_complex',
'[0]vflip[s0];'
'[s0]split=2[s1][s2];'
'[s1]trim=end_frame=20:start_frame=10[s3];'
'[s2]trim=end_frame=40:start_frame=30[s4];'
'[s3][s4]concat=n=2[s5];'
'[1]crop=158:112:10:10[s6];'
'[s6]hflip[s7];'
'[s5][s7]overlay=eof_action=repeat[s8];'
'[s8]drawbox=50:50:120:120:red:t=5[s9]',
'-map',
'[s9]',
TEST_OUTPUT_FILE1,
'-y',
]
def test_combined_output():
i1 = ffmpeg.input(TEST_INPUT_FILE1)
i2 = ffmpeg.input(TEST_OVERLAY_FILE)
out = ffmpeg.output(i1, i2, TEST_OUTPUT_FILE1)
assert out.get_args() == [
'-i',
TEST_INPUT_FILE1,
'-i',
TEST_OVERLAY_FILE,
'-map',
'0',
'-map',
'1',
TEST_OUTPUT_FILE1,
]
@pytest.mark.parametrize('use_shorthand', [True, False])
def test_filter_with_selector(use_shorthand):
i = ffmpeg.input(TEST_INPUT_FILE1)
if use_shorthand:
v1 = i.video.hflip()
a1 = i.audio.filter('aecho', 0.8, 0.9, 1000, 0.3)
else:
v1 = i['v'].hflip()
a1 = i['a'].filter('aecho', 0.8, 0.9, 1000, 0.3)
out = ffmpeg.output(a1, v1, TEST_OUTPUT_FILE1)
assert out.get_args() == [
'-i',
TEST_INPUT_FILE1,
'-filter_complex',
'[0:a]aecho=0.8:0.9:1000:0.3[s0];' '[0:v]hflip[s1]',
'-map',
'[s0]',
'-map',
'[s1]',
TEST_OUTPUT_FILE1,
]
def test_get_item_with_bad_selectors():
input = ffmpeg.input(TEST_INPUT_FILE1)
with pytest.raises(ValueError) as excinfo:
input['a']['a']
assert str(excinfo.value).startswith('Stream already has a selector:')
with pytest.raises(TypeError) as excinfo:
input[:'a']
assert str(excinfo.value).startswith("Expected string index (e.g. 'a')")
with pytest.raises(TypeError) as excinfo:
input[5]
assert str(excinfo.value).startswith("Expected string index (e.g. 'a')")
def _get_complex_filter_asplit_example():
split = ffmpeg.input(TEST_INPUT_FILE1).vflip().asplit()
split0 = split[0]
split1 = split[1]
return (
ffmpeg.concat(
split0.filter('atrim', start=10, end=20),
split1.filter('atrim', start=30, end=40),
)
.output(TEST_OUTPUT_FILE1)
.overwrite_output()
)
def test_filter_concat__video_only():
in1 = ffmpeg.input('in1.mp4')
in2 = ffmpeg.input('in2.mp4')
args = ffmpeg.concat(in1, in2).output('out.mp4').get_args()
assert args == [
'-i',
'in1.mp4',
'-i',
'in2.mp4',
'-filter_complex',
'[0][1]concat=n=2[s0]',
'-map',
'[s0]',
'out.mp4',
]
def test_filter_concat__audio_only():
in1 = ffmpeg.input('in1.mp4')
in2 = ffmpeg.input('in2.mp4')
args = ffmpeg.concat(in1, in2, v=0, a=1).output('out.mp4').get_args()
assert args == [
'-i',
'in1.mp4',
'-i',
'in2.mp4',
'-filter_complex',
'[0][1]concat=a=1:n=2:v=0[s0]',
'-map',
'[s0]',
'out.mp4',
]
def test_filter_concat__audio_video():
in1 = ffmpeg.input('in1.mp4')
in2 = ffmpeg.input('in2.mp4')
joined = ffmpeg.concat(in1.video, in1.audio, in2.hflip(), in2['a'], v=1, a=1).node
args = ffmpeg.output(joined[0], joined[1], 'out.mp4').get_args()
assert args == [
'-i',
'in1.mp4',
'-i',
'in2.mp4',
'-filter_complex',
'[1]hflip[s0];[0:v][0:a][s0][1:a]concat=a=1:n=2:v=1[s1][s2]',
'-map',
'[s1]',
'-map',
'[s2]',
'out.mp4',
]
def test_filter_concat__wrong_stream_count():
in1 = ffmpeg.input('in1.mp4')
in2 = ffmpeg.input('in2.mp4')
with pytest.raises(ValueError) as excinfo:
ffmpeg.concat(in1.video, in1.audio, in2.hflip(), v=1, a=1).node
assert (
str(excinfo.value)
== 'Expected concat input streams to have length multiple of 2 (v=1, a=1); got 3'
)
def test_filter_asplit():
out = _get_complex_filter_asplit_example()
args = out.get_args()
assert args == [
'-i',
TEST_INPUT_FILE1,
'-filter_complex',
'[0]vflip[s0];[s0]asplit=2[s1][s2];[s1]atrim=end=20:start=10[s3];[s2]atrim=end=40:start=30[s4];[s3]'
'[s4]concat=n=2[s5]',
'-map',
'[s5]',
TEST_OUTPUT_FILE1,
'-y',
]
def test__output__bitrate():
args = (
ffmpeg.input('in')
.output('out', video_bitrate=1000, audio_bitrate=200)
.get_args()
)
assert args == ['-i', 'in', '-b:v', '1000', '-b:a', '200', 'out']
@pytest.mark.parametrize('video_size', [(320, 240), '320x240'])
def test__output__video_size(video_size):
args = ffmpeg.input('in').output('out', video_size=video_size).get_args()
assert args == ['-i', 'in', '-video_size', '320x240', 'out']
def test_filter_normal_arg_escape():
"""Test string escaping of normal filter args (e.g. ``font`` param of ``drawtext`` filter)."""
def _get_drawtext_font_repr(font):
"""Build a command-line arg using drawtext ``font`` param and extract the ``-filter_complex`` arg."""
args = (
ffmpeg.input('in')
.drawtext('test', font='a{}b'.format(font))
.output('out')
.get_args()
)
assert args[:3] == ['-i', 'in', '-filter_complex']
assert args[4:] == ['-map', '[s0]', 'out']
match = re.match(
r'\[0\]drawtext=font=a((.|\n)*)b:text=test\[s0\]', args[3], re.MULTILINE
)
assert match is not None, 'Invalid -filter_complex arg: {!r}'.format(args[3])
return match.group(1)
expected_backslash_counts = {
'x': 0,
'\'': 3,
'\\': 3,
'%': 0,
':': 2,
',': 1,
'[': 1,
']': 1,
'=': 2,
'\n': 0,
}
for ch, expected_backslash_count in list(expected_backslash_counts.items()):
expected = '{}{}'.format('\\' * expected_backslash_count, ch)
actual = _get_drawtext_font_repr(ch)
assert expected == actual
def test_filter_text_arg_str_escape():
"""Test string escaping of normal filter args (e.g. ``text`` param of ``drawtext`` filter)."""
def _get_drawtext_text_repr(text):
"""Build a command-line arg using drawtext ``text`` param and extract the ``-filter_complex`` arg."""
args = ffmpeg.input('in').drawtext('a{}b'.format(text)).output('out').get_args()
assert args[:3] == ['-i', 'in', '-filter_complex']
assert args[4:] == ['-map', '[s0]', 'out']
match = re.match(r'\[0\]drawtext=text=a((.|\n)*)b\[s0\]', args[3], re.MULTILINE)
assert match is not None, 'Invalid -filter_complex arg: {!r}'.format(args[3])
return match.group(1)
expected_backslash_counts = {
'x': 0,
'\'': 7,
'\\': 7,
'%': 4,
':': 2,
',': 1,
'[': 1,
']': 1,
'=': 2,
'\n': 0,
}
for ch, expected_backslash_count in list(expected_backslash_counts.items()):
expected = '{}{}'.format('\\' * expected_backslash_count, ch)
actual = _get_drawtext_text_repr(ch)
assert expected == actual
# def test_version():
# subprocess.check_call(['ffmpeg', '-version'])
def test__compile():
out_file = ffmpeg.input('dummy.mp4').output('dummy2.mp4')
assert out_file.compile() == ['ffmpeg', '-i', 'dummy.mp4', 'dummy2.mp4']
assert out_file.compile(cmd='ffmpeg.old') == [
'ffmpeg.old',
'-i',
'dummy.mp4',
'dummy2.mp4',
]
@pytest.mark.parametrize('pipe_stdin', [True, False])
@pytest.mark.parametrize('pipe_stdout', [True, False])
@pytest.mark.parametrize('pipe_stderr', [True, False])
def test__run_async(mocker, pipe_stdin, pipe_stdout, pipe_stderr):
process__mock = mock.Mock()
popen__mock = mocker.patch.object(subprocess, 'Popen', return_value=process__mock)
stream = _get_simple_example()
process = ffmpeg.run_async(
stream, pipe_stdin=pipe_stdin, pipe_stdout=pipe_stdout, pipe_stderr=pipe_stderr
)
assert process is process__mock
expected_stdin = subprocess.PIPE if pipe_stdin else None
expected_stdout = subprocess.PIPE if pipe_stdout else None
expected_stderr = subprocess.PIPE if pipe_stderr else None
(args,), kwargs = popen__mock.call_args
assert args == ffmpeg.compile(stream)
assert kwargs == dict(
stdin=expected_stdin, stdout=expected_stdout, stderr=expected_stderr
)
def test__run():
stream = _get_complex_filter_example()
out, err = ffmpeg.run(stream)
assert out is None
assert err is None
@pytest.mark.parametrize('capture_stdout', [True, False])
@pytest.mark.parametrize('capture_stderr', [True, False])
def test__run__capture_out(mocker, capture_stdout, capture_stderr):
mocker.patch.object(ffmpeg._run, 'compile', return_value=['echo', 'test'])
stream = _get_simple_example()
out, err = ffmpeg.run(
stream, capture_stdout=capture_stdout, capture_stderr=capture_stderr
)
if capture_stdout:
assert out == 'test\n'.encode()
else:
assert out is None
if capture_stderr:
assert err == ''.encode()
else:
assert err is None
def test__run__input_output(mocker):
mocker.patch.object(ffmpeg._run, 'compile', return_value=['cat'])
stream = _get_simple_example()
out, err = ffmpeg.run(stream, input='test'.encode(), capture_stdout=True)
assert out == 'test'.encode()
assert err is None
@pytest.mark.parametrize('capture_stdout', [True, False])
@pytest.mark.parametrize('capture_stderr', [True, False])
def test__run__error(mocker, capture_stdout, capture_stderr):
mocker.patch.object(ffmpeg._run, 'compile', return_value=['ffmpeg'])
stream = _get_complex_filter_example()
with pytest.raises(ffmpeg.Error) as excinfo:
out, err = ffmpeg.run(
stream, capture_stdout=capture_stdout, capture_stderr=capture_stderr
)
assert str(excinfo.value) == 'ffmpeg error (see stderr output for detail)'
out = excinfo.value.stdout
err = excinfo.value.stderr
if capture_stdout:
assert out == ''.encode()
else:
assert out is None
if capture_stderr:
assert err.decode().startswith('ffmpeg version')
else:
assert err is None
def test__run__multi_output():
in_ = ffmpeg.input(TEST_INPUT_FILE1)
out1 = in_.output(TEST_OUTPUT_FILE1)
out2 = in_.output(TEST_OUTPUT_FILE2)
ffmpeg.run([out1, out2], overwrite_output=True)
def test__run__dummy_cmd():
stream = _get_complex_filter_example()
ffmpeg.run(stream, cmd='true')
def test__run__dummy_cmd_list():
stream = _get_complex_filter_example()
ffmpeg.run(stream, cmd=['true', 'ignored'])
def test__filter__custom():
stream = ffmpeg.input('dummy.mp4')
stream = ffmpeg.filter(stream, 'custom_filter', 'a', 'b', kwarg1='c')
stream = ffmpeg.output(stream, 'dummy2.mp4')
assert stream.get_args() == [
'-i',
'dummy.mp4',
'-filter_complex',
'[0]custom_filter=a:b:kwarg1=c[s0]',
'-map',
'[s0]',
'dummy2.mp4',
]
def test__filter__custom_fluent():
stream = (
ffmpeg.input('dummy.mp4')
.filter('custom_filter', 'a', 'b', kwarg1='c')
.output('dummy2.mp4')
)
assert stream.get_args() == [
'-i',
'dummy.mp4',
'-filter_complex',
'[0]custom_filter=a:b:kwarg1=c[s0]',
'-map',
'[s0]',
'dummy2.mp4',
]
def test__merge_outputs():
in_ = ffmpeg.input('in.mp4')
out1 = in_.output('out1.mp4')
out2 = in_.output('out2.mp4')
assert ffmpeg.merge_outputs(out1, out2).get_args() == [
'-i',
'in.mp4',
'out1.mp4',
'out2.mp4',
]
assert ffmpeg.get_args([out1, out2]) == ['-i', 'in.mp4', 'out2.mp4', 'out1.mp4']
def test__input__start_time():
assert ffmpeg.input('in', ss=10.5).output('out').get_args() == [
'-ss',
'10.5',
'-i',
'in',
'out',
]
assert ffmpeg.input('in', ss=0.0).output('out').get_args() == [
'-ss',
'0.0',
'-i',
'in',
'out',
]
def test_multi_passthrough():
out1 = ffmpeg.input('in1.mp4').output('out1.mp4')
out2 = ffmpeg.input('in2.mp4').output('out2.mp4')
out = ffmpeg.merge_outputs(out1, out2)
assert ffmpeg.get_args(out) == [
'-i',
'in1.mp4',
'-i',
'in2.mp4',
'out1.mp4',
'-map',
'1',
'out2.mp4',
]
assert ffmpeg.get_args([out1, out2]) == [
'-i',
'in2.mp4',
'-i',
'in1.mp4',
'out2.mp4',
'-map',
'1',
'out1.mp4',
]
def test_passthrough_selectors():
i1 = ffmpeg.input(TEST_INPUT_FILE1)
args = ffmpeg.output(i1['1'], i1['2'], TEST_OUTPUT_FILE1).get_args()
assert args == [
'-i',
TEST_INPUT_FILE1,
'-map',
'0:1',
'-map',
'0:2',
TEST_OUTPUT_FILE1,
]
def test_mixed_passthrough_selectors():
i1 = ffmpeg.input(TEST_INPUT_FILE1)
args = ffmpeg.output(i1['1'].hflip(), i1['2'], TEST_OUTPUT_FILE1).get_args()
assert args == [
'-i',
TEST_INPUT_FILE1,
'-filter_complex',
'[0:1]hflip[s0]',
'-map',
'[s0]',
'-map',
'0:2',
TEST_OUTPUT_FILE1,
]
def test_pipe():
width = 32
height = 32
frame_size = width * height * 3 # 3 bytes for rgb24
frame_count = 10
start_frame = 2
out = (
ffmpeg.input(
'pipe:0',
format='rawvideo',
pixel_format='rgb24',
video_size=(width, height),
framerate=10,
)
.trim(start_frame=start_frame)
.output('pipe:1', format='rawvideo')
)
args = out.get_args()
assert args == [
'-f',
'rawvideo',
'-video_size',
'{}x{}'.format(width, height),
'-framerate',
'10',
'-pixel_format',
'rgb24',
'-i',
'pipe:0',
'-filter_complex',
'[0]trim=start_frame=2[s0]',
'-map',
'[s0]',
'-f',
'rawvideo',
'pipe:1',
]
cmd = ['ffmpeg'] + args
p = subprocess.Popen(
cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE
)
in_data = bytes(
bytearray([random.randint(0, 255) for _ in range(frame_size * frame_count)])
)
p.stdin.write(in_data) # note: this could block, in which case need to use threads
p.stdin.close()
out_data = p.stdout.read()
assert len(out_data) == frame_size * (frame_count - start_frame)
assert out_data == in_data[start_frame * frame_size :]
def test__probe():
data = ffmpeg.probe(TEST_INPUT_FILE1)
assert set(data.keys()) == {'format', 'streams'}
assert data['format']['duration'] == '7.036000'
def test__probe__exception():
with pytest.raises(ffmpeg.Error) as excinfo:
ffmpeg.probe(BOGUS_INPUT_FILE)
assert str(excinfo.value) == 'ffprobe error (see stderr output for detail)'
assert 'No such file or directory'.encode() in excinfo.value.stderr
def test__probe__extra_args():
data = ffmpeg.probe(TEST_INPUT_FILE1, show_frames=None)
assert set(data.keys()) == {'format', 'streams', 'frames'}
def get_filter_complex_input(flt, name):
m = re.search(r'\[([^]]+)\]{}(?=[[;]|$)'.format(name), flt)
if m:
return m.group(1)
else:
return None
def get_filter_complex_outputs(flt, name):
m = re.search(r'(^|[];]){}((\[[^]]+\])+)(?=;|$)'.format(name), flt)
if m:
return m.group(2)[1:-1].split('][')
else:
return None
def test__get_filter_complex_input():
assert get_filter_complex_input("", "scale") is None
assert get_filter_complex_input("scale", "scale") is None
assert get_filter_complex_input("scale[s3][s4];etc", "scale") is None
assert get_filter_complex_input("[s2]scale", "scale") == "s2"
assert get_filter_complex_input("[s2]scale;etc", "scale") == "s2"
assert get_filter_complex_input("[s2]scale[s3][s4];etc", "scale") == "s2"
def test__get_filter_complex_outputs():
assert get_filter_complex_outputs("", "scale") is None
assert get_filter_complex_outputs("scale", "scale") is None
assert get_filter_complex_outputs("scalex[s0][s1]", "scale") is None
assert get_filter_complex_outputs("scale[s0][s1]", "scale") == ['s0', 's1']
assert get_filter_complex_outputs("[s5]scale[s0][s1]", "scale") == ['s0', 's1']
assert get_filter_complex_outputs("[s5]scale[s1][s0]", "scale") == ['s1', 's0']
assert get_filter_complex_outputs("[s5]scale[s1]", "scale") == ['s1']
assert get_filter_complex_outputs("[s5]scale[s1];x", "scale") == ['s1']
assert get_filter_complex_outputs("y;[s5]scale[s1];x", "scale") == ['s1']
def test__multi_output_edge_label_order():
scale2ref = ffmpeg.filter_multi_output(
[ffmpeg.input('x'), ffmpeg.input('y')], 'scale2ref'
)
out = ffmpeg.merge_outputs(
scale2ref[1].filter('scale').output('a'),
scale2ref[10000].filter('hflip').output('b'),
)
args = out.get_args()
flt_cmpl = args[args.index('-filter_complex') + 1]
out1, out2 = get_filter_complex_outputs(flt_cmpl, 'scale2ref')
assert out1 == get_filter_complex_input(flt_cmpl, 'scale')
assert out2 == get_filter_complex_input(flt_cmpl, 'hflip')