Read a raw or headerless input (forced format & demuxer options)¶

Some inputs carry no header for the demuxer to probe — raw .yuv video, raw .pcm audio, a stream with a misleading extension. For those, name the demuxer with InputFormat and hand it the geometry it can't infer through DemuxerOption (spec 0024).

Raw video¶

A raw rawvideo stream is pixels and nothing else, so the demuxer needs the size, pixel format, and frame rate:

cmd := afmpeg.NewCommand(
    afmpeg.WithInput("frames.yuv", afmpeg.InputFormat("rawvideo"),
        afmpeg.DemuxerOption("video_size", "1280x720"),
        afmpeg.DemuxerOption("pixel_format", "yuv420p"),
        afmpeg.DemuxerOption("framerate", "25")),
    afmpeg.WithFilterComplex("[0:v]null[v]"),
    afmpeg.WithOutput("out.mp4", afmpeg.Map("[v]"), afmpeg.VideoCodec("libopenh264")),
)

Raw audio¶

Raw PCM is the same shape — a sample format demuxer (s16le, f32le, …) plus the rate and channel layout:

afmpeg.WithInput("tone.pcm", afmpeg.InputFormat("s16le"),
    afmpeg.DemuxerOption("sample_rate", "48000"),
    afmpeg.DemuxerOption("ch_layout", "mono"))

Forcing the demuxer for a mislabelled file¶

InputFormat also overrides auto-probing when a container's extension would mislead it — an mp4 served as clip.bin, say:

afmpeg.WithInput("clip.bin", afmpeg.InputFormat("mp4"))

Options are checked, not swallowed¶

A DemuxerOption the demuxer doesn't recognise is a typed error, not a silent no-op — a typo or a wrong-demuxer option fails loudly rather than producing quietly-wrong output. That is the same "exactly as capable as it claims" posture the whole job spec takes.

Selecting a specific stream¶

When an input has several streams of one type, index the one you want in a filtergraph pad: [0:v:1] feeds the graph from the second video stream (the unindexed [0:v] takes the best one). The same in:type:index grammar names a copied stream in Map.