+genpts passed as option to ffmpeg doesn't work

[aseemk98]

Overview

I am receiving an mpeg2ts on localhost:7000. The issue is that the stream doesn't contain any pts/dts information at all. Hence, I used the genpts flag in in fflags to generate these on the go. Here is my test code:

import av
import os

                                         
options = {"fflags": "+genpts"}

                                        
container = av.open(                         
    file="udp://localhost:7000",                          
    format="mpegts",            
    mode="r",                   
    options=options,
    timeout=5                                        
)
container.gen_pts = True     
print("Default value of gen_pts:", container.gen_pts)                                            

for packet in container.demux():
    print(f"Packet PTS: {packet.pts}, DTS: {packet.dts}") 
    for frame in packet.decode():
        print(f"Frame PTS: {frame.pts}, DTS: {frame.dts}, Time: {frame.time}")

Expected behavior

To verify whether its an issue with my ffmpeg installation, I used ffmpeg with the genpts option to generate a .ts file and then used ffprobe to check for pts/dts values.
ffmpeg -fflags +genpts -i udp://localhost:7000 -c copy output.ts followed by
ffprobe -select_streams v -show_frames output.ts | less

This does embed pts and dts for every frame:

[FRAME]
media_type=video
stream_index=0
key_frame=1
pts=126000
pts_time=1.400000
pkt_dts=126000
pkt_dts_time=1.400000
best_effort_timestamp=126000
best_effort_timestamp_time=1.400000
duration=3000
duration_time=0.033333
pkt_pos=564
pkt_size=48211
width=1920
height=1080
crop_top=0
crop_bottom=0
crop_left=0
crop_right=0
pix_fmt=yuv420p
sample_aspect_ratio=1:1
pict_type=I
interlaced_frame=0
top_field_first=0
repeat_pict=0
color_range=tv
color_space=unknown
color_primaries=bt709
color_transfer=unknown
chroma_location=left
[/FRAME]

Actual behavior

But when I set the same option through the PyAV code above, all the pts/dts values are printed as None.

Versions

• OS: macOS 13.4
• PyAV runtime:

PyAV v10.0.0
library configuration: --disable-static --enable-shared --libdir=/tmp/vendor/lib --prefix=/tmp/vendor --arch=arm64 --enable-cross-compile --disable-alsa --disable-doc --disable-mediafoundation --enable-fontconfig --enable-gmp --disable-gnutls --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --disable-libxcb --enable-libxml2 --enable-libxvid --enable-lzma --enable-version3 --enable-zlib
library license: GPL version 3 or later
libavcodec     59. 37.100
libavdevice    59.  7.100
libavfilter     8. 44.100
libavformat    59. 27.100
libavutil      57. 28.100
libswresample   4.  7.100
libswscale      6.  7.100

Research

I have done the following:

• Checked the PyAV documentation
• Searched on Google
• Searched on Stack Overflow
• Looked through old GitHub issues