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• What is this "fixing the build scripts" for compiling x264 ?

  29 mai 2020, par Blake Senftner

  I am trying to compile an all static build of source-customized ffmpeg libraries with the additional codecs from VideoLAN, such as their x264 codec. I am ultimately building for use in Windows with Visual Studio 2015 C++, so I am comparing a few compiling guides for my instructions.

  



  In the guide linked below (I located via Google searches) shows how to compile x264 with the VS2015 toolchain in MSYS2 without any special steps :
https://gist.github.com/RangelReale/3e6392289d8ba1a52b6e70cdd7e10282

  



  While in this other guide, offered by the compiling guide pages from ffmpeg's web site, it includes steps for "fixing the build scripts" for x264 :
https://www.roxlu.com/2019/062/compiling-ffmpeg-with-x264-on-windows-10-using-msvc

  



  Problem being, when I "fix the build scripts" the configure script no longer finds a C compiler. Building with the first guide seems to work, but it was also written nearly 2 years ago, so perhaps the ffmpeg guide is doing some important fix ? I don't know.

  



  I am :

  



  

  1. Running a "VS2015 x64 Native Tools Command Prompt"

  


  2. launching a pacman loaded msys2 shell via "msys2_shell.cmd -mingw64 -use-full-path"

  


  3. git cloning http://git.videolan.org/git/x264.git

  


  



  and at this point the two compiling guides vary, the first guide just cd's into x264 and runs configure while the other guide does some curl download of a config.guess file and then some sed manipulation of ./configure. Considering these instructions are "endorsed" by the ffmpeg site, I am left wondering what that is doing and how critical is it that these "special" steps cause my x264 configure to fail.

  


• Why does ffmpeg return "No such file or directory"

  4 juillet 2020, par JackNewman

  I'm trying to split a video file into 2 second increments and then merge the video back together.

  


  source_vid_path = r"C:\SplitAndMergeVids\Before\before.mp4"
ffcat_path = r'C:\SplitAndMergeVids\Chunk\video.ffcat'
chunks_path = r'C:\SplitAndMergeVids\Chunk\chunk-%03d.mp4'
segments_time = '2'
cmd_input = rf'ffmpeg -fflags +genpts -i {source_vid_path} -map 0 -c copy -f segment -segment_format mp4 -segment_time {segments_time} -segment_list {ffcat_path} -reset_timestamps 1 -v error {chunks_path}'
output = str(subprocess.run(cmd_input, shell=True, capture_output=True))
print(output)

output_path = r'C:\SplitAndMergeVids\Output\output.mp4'
second_input = rf'ffmpeg -y -v error -i {ffcat_path} -map 0 -c copy {output_path}'
output = str(subprocess.run(second_input, shell=True, capture_output=True))
print(output)


  


  First subprocess runs perfectly although the second outputs returns

  


  "Impossible to open 'chunk-000.mp4'\r\nC:\\SplitAndMergeVids\\Chunk\\video.ffcat: No such file or directory".


  


  Full output looks like

  


  CompletedProcess(args='ffmpeg -fflags +genpts -i C:\\SplitAndMergeVids\\Before\\before.mp4 -map 0 -c copy -f segment -segment_format mp4 -segment_time 2 -segment_list C:\\SplitAndMergeVids\\Chunk\\video.ffcat -reset_timestamps 1 -v error C:\\SplitAndMergeVids\\Chunk\\chunk-%03d.mp4', returncode=0, stdout=b'', stderr=b'')
CompletedProcess(args='ffmpeg -y -v error -i C:\\SplitAndMergeVids\\Chunk\\video.ffcat -map 0 -c copy C:\\SplitAndMergeVids\\Output\\output.mp4', returncode=1, stdout=b'', stderr=b"[concat @ 0000028691a6c6c0] Impossible to open 'chunk-000.mp4'\r\nC:\\SplitAndMergeVids\\Chunk\\video.ffcat: No such file or directory\r\n")


  


  When I run cmd_input and second_input manually in cmd, everything functions perfectly. I don't understand how in the first command I am making a file at "ffcat_path", then in the second command I'm using the same "ffcat_path" and it returns "No such file or directory" when it certainly does exist.

  


• Edit H264 video stream header information ("start_pts" and "start_time")

  27 juin 2020, par David

  I have a video clip that appears to be slightly corrupted. Does not play on VLC but works on Potplayer. I used FFprobe to get information on the video.

  


  The problem appears to be with the start points of the video stream :

  


  time_base=1/90000
start_pts=585050940
start_time=6500.566000
duration_ts=585050940
duration=6500.566000
bit_rate=3123218


  


  I'm just wondering whether it is possible to manually edit the "start_pts" and "start_time" to 0 ? Is there any specific software to do this ? Due to large size of video file, I couldn't load it in Notepad++.

  


  Full ffprobe output shown below :

  


  # ffprobe output

[streams.stream.0]
index=0
codec_name=h264
codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
profile=unknown
codec_type=video
codec_time_base=1/60
codec_tag_string=avc1
codec_tag=0x31637661
width=1920
height=1080
coded_width=1920
coded_height=1080
closed_captions=0
has_b_frames=0
sample_aspect_ratio=N/A
display_aspect_ratio=N/A
pix_fmt=unknown
level=-99
color_range=unknown
color_space=unknown
color_transfer=unknown
color_primaries=unknown
chroma_location=unspecified
field_order=unknown
timecode=N/A
refs=1
is_avc=true
nal_length_size=4
id=N/A
r_frame_rate=30/1
avg_frame_rate=30/1
time_base=1/90000
start_pts=585050940
start_time=6500.566000
duration_ts=585050940
duration=6500.566000
bit_rate=3123218
max_bit_rate=N/A
bits_per_raw_sample=N/A
nb_frames=195017
nb_read_frames=N/A
nb_read_packets=N/A

[streams.stream.0.disposition]
default=1
dub=0
original=0
comment=0
lyrics=0
karaoke=0
forced=0
hearing_impaired=0
visual_impaired=0
clean_effects=0
attached_pic=0
timed_thumbnails=0

[streams.stream.0.tags]
language=und
handler_name=VideoHandler

[streams.stream.1]
index=1
codec_name=aac
codec_long_name=AAC (Advanced Audio Coding)
profile=LC
codec_type=audio
codec_time_base=1/48000
codec_tag_string=mp4a
codec_tag=0x6134706d
sample_fmt=fltp
sample_rate=48000
channels=2
channel_layout=stereo
bits_per_sample=0
id=N/A
r_frame_rate=0/0
avg_frame_rate=0/0
time_base=1/48000
start_pts=0
start_time=0.000000
duration_ts=312029184
duration=6500.608000
bit_rate=189376
max_bit_rate=189376
bits_per_raw_sample=N/A
nb_frames=304718
nb_read_frames=N/A
nb_read_packets=N/A

[streams.stream.1.disposition]
default=1
dub=0
original=0
comment=0
lyrics=0
karaoke=0
forced=0
hearing_impaired=0
visual_impaired=0
clean_effects=0
attached_pic=0
timed_thumbnails=0

[streams.stream.1.tags]
language=eng
handler_name=SoundHandler

[format]
filename=D\:\\Start\\test.mp4
nb_streams=2
nb_programs=0
format_name=mov,mp4,m4a,3gp,3g2,mj2
format_long_name=QuickTime / MOV
start_time=0.000000
duration=6500.608000
size=2703218140
bit_rate=3326726
probe_score=100

[format.tags]
major_brand=isom
minor_version=512
compatible_brands=isomiso2avc1mp41