ffmpeg produces “is_avc” = false with h264_nvenc & tee muxer

[Areeb Mohamed]

Summary of the bug: I have a really strange problem when using "-c:v h264_nvenc" and "tee muxer" both then the produced output file is having "is_avc=false" even i have checked the same input matroska file with another server running with Intel QuickSync "-c:v h264_qsv" with the same command then the produced output file is "is_avc=true".

The main reason that i want the "is_avc=true" is because the files must be played using "nginx-vod-module" which requires the AVC video format to be streamed.

How to reproduce:

% /root/ffmpeg  -y -t 00:00:50 -i "testinput.mkv" -filter_complex "[0:v]split=2[s0][s1];[s0]scale=-2:720[v0];[s1]scale=-2:360[v1]" -map "[v0]" -map "[v1]" -map 0:a -c:v h264_nvenc -b:v:0 1100k -b:v:1 600k -profile:v:0 main -profile:v:1 baseline -level:v:0 4 -level:v:1 3.1 -ac 2 -c:a aac -b:a 128k -af "aresample=async=1000:first_pts=0"  -f tee "[select=\'v:0,a\']testoutput.mp4|[select=\'v:1,a\']testoutput-360.mp4"

ffmpeg version: N-91182-gbdf1bbd Copyright (c) 2000-2018 the FFmpeg developers   built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-28)

built on CentOS 7.3.1611 + NVIDIA Driver (NVIDIA-Linux-x86_64-390.77.run) + CUDA (cuda-repo-rhel7-9-2-local-9.2.88-1.x86_64.rpm) + NVIDIA K2000 GPU Card Installed

---

Running ffprobe for the output file to check "is_avc":

ffprobe -v quiet -print_format json -show_format -show_streams testoutput.mp4

---

 {
    "streams": [
        {
            "index": 0,
            "codec_name": "h264",
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
            "profile": "Main",
            "codec_type": "video",
            "codec_time_base": "1001/48000",
            "codec_tag_string": "avc1",
            "codec_tag": "0x31637661",
            "width": 1280,
            "height": 720,
            "coded_width": 1280,
            "coded_height": 720,
            "has_b_frames": 0,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "16:9",
            "pix_fmt": "yuv420p",
            "level": 40,
            "chroma_location": "left",
            "refs": 1,
            "is_avc": "false",
            "nal_length_size": "0",
            "r_frame_rate": "24000/1001",
            "avg_frame_rate": "24000/1001",
            "time_base": "1/24000",
            "start_pts": 984,
            "start_time": "0.041000",
            "duration_ts": 1201200,
            "duration": "50.050000",
            "bit_rate": "845035",
            "bits_per_raw_sample": "8",
            "nb_frames": "1199",
            "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
            },
            "tags": {
                "language": "und",
                "handler_name": "VideoHandler"
            }
        },
        {
            "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,
            "r_frame_rate": "0/0",
            "avg_frame_rate": "0/0",
            "time_base": "1/48000",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 2401488,
            "duration": "50.031000",
            "bit_rate": "129153",
            "max_bit_rate": "129153",
            "nb_frames": "2346",
            "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
            },
            "tags": {
                "language": "ger",
                "handler_name": "SoundHandler"
            }
        }
    ],
    "format": {
        "filename": "testoutput.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": "50.031000",
        "size": "6116472",
        "bit_rate": "978029",
        "probe_score": 100,
        "tags": {
            "major_brand": "isom",
            "minor_version": "512",
            "compatible_brands": "isomiso2avc1mp41",
            "encoder": "Lavf58.17.100"
        }
    }
}

Please anyone can help me why is the output video file is getting "is_avc=false" ?

Is there any option to force it ?

Thank you

[Areeb Mohamed]

Thanks to Gyan (​https://stackoverflow.com/questions/51844515/ffmpeg-produces-is-avc-false-with-h264-nvenc-tee-muxer) who helped me to solve this issue by adding:
-flags +global_header after the -c:v h264_nvenc prop.

Solved!.