AviSource

Revision as of 04:28, 9 January 2016

AviSource takes one or more file names and returns a clip with all files joined end to end. Note the file formats must be compatible - see Joining Clips below.

WavSource will open a WAV file, or the audio stream from an AVI file. This can be used, for example, if your video stream is damaged or its compression method is not supported on your system.

Syntax and Parameters

AviSource(string filename [, ...] [, bool "audio", string "pixel_type", string "fourCC", int "vtrack", int "atrack"])
AviFileSource(string filename [, ...] [, bool "audio", string "pixel_type", string "fourCC", int "vtrack", int "atrack"])
OpenDMLSource(string filename [, ...] [, bool "audio", string "pixel_type", string "fourCC", int "vtrack", int "atrack"])

WavSource(string filename [, ...])

string  filename =

One or more file names. The files will be joined into a single clip with UnalignedSplice. Note the file formats must be compatible - see Joining Clips below.

bool  audio = true

If true, load the first audio stream, or the stream specified by atrack if present. If false, audio is disabled.

string  pixel_type = "FULL"

Chooses the output color format of the decompressor. Valid values are listed in the table below. This argument has no effect if the video is uncompressed, because no decompressor will be used in that case.

• If omitted or "FULL", AviSynth will use the first format supported by the decompressor, in the order shown in the table below.
• If "AUTO", AviSynth will use the alternate (older) order as shown.

Valid pixel_type values, listed by decoding priority (high to low)
FULL	YV24	YV16	YV12	YV411	YUY2	RGB32	RGB24	Y8
AUTO			YV12		YUY2	RGB32	RGB24	Y8

In other words, if you don't specify anything, it will try to output YV24; if that isn't possible it tries YV16, and if that isn't possible it tries YV12, etc ...

For planar color formats, adding a '+' prefix, e.g. AviSource(..., pixel_type="+YV12"), tells AviSynth the video rows are DWORD aligned in memory instead of packed. This can fix skew or tearing of the decoded video when the width of the picture is not divisible by 4.

string  fourCC = (auto from source)

Forces use of a different codec than the default, taken from the FourCC of the video stream.

int  vtrack = 0

Specify a numbered video track. Track numbers start from zero, and are guaranteed to be continuous (i.e. there must be a track 1 if there is a track 0 and a track 2). If no video stream numbered vtrack exists, an error will be raised.

int  atrack = 0

Specify a numbered audio track. Track numbers start from zero, and are guaranteed to be continuous (i.e. there must be a track 1 if there is a track 0 and a track 2). If no audio stream numbered atrack exists, no error will be raised, and no audio will be returned.

Notes

Joining clips

• There is a limit of (about 50) AviSource calls in script. See discussion.

• File formats must be compatible; that means:

1. Both clips have the same height and width.
2. Both clips have the same frame rate (precisely the same, not approximately)
3. Both clips have the same audio sample rate, bit depth and number of channels.
4. Both clips have the same color format (as presented by the decoder)

• See the VirtualDub blog post Appending streams and mismatch errors for a more in-depth explanation.

Windows 7 users

WavSource under Windows 7 is unable to load WAV files with 32-bit IEEE Float samples having the WAVEFORMAT structure. You can use ConvertAudioTo16bit or you can use ffmpeg to rewrite the header to an extensible format (just do a stream copy, -a:copy; it always writes extensible headers).

Helpful hints

• Sometimes the colors will be distorted when loading a DivX clip in AviSynth v2.5 (the chroma channels U and V are swapped), due to a bug in DivX (5.02 and older). You can use SwapUV to correct it.

• AVISource can also open DV type 1 video input (only video, not audio).

• Some MJPEG/DV codecs do not give correct CCIR 601 compliant output when using AVISource. The problem could arise if the input and output color format of the codec are different. For example if the input color format is YUY2, while the output format is RGB, or vice versa. There are two ways to resolve it:

1. Force the same output as the input color format. Thus for example (if the input is RGB):

AviSource("file.avi", pixel_type="RGB32")

2. Correct it with the filter ColorYUV:

AviSource("file.avi").ColorYUV(levels="PC->TV")

More on codecs

• MJPEG codecs
• DV codecs

Examples

# C programmers note: backslashes are not doubled; forward slashes work too
AVISource("d:\capture.avi")
AVISource("c:/capture/00.avi")
WAVSource("f:\soundtrack.wav")
WAVSource("f:/soundtrack.wav")

# The following statements do the same thing:
# (to join clips, file formats must be compatible - see Notes on this page)
AviSource("cap1.avi") + AviSource("cap2.avi")
AVISource("cap1.avi", "cap2.avi")

# Disable audio and request RGB32 decompression
AVISource("cap.avi", audio=false, "RGB32")

# Open a DV, forcing the Canopus DV Codec
AviSource("cap.avi", fourCC="CDVC")

# Open a file, forcing the XviD Codec
AviSource("cap.avi", fourCC="XVID")

# Splice two clips together, where one of them contains no audio.
A = AviSource("FileA.avi")
B = AviSource("FileB.avi") # No audio stream
A ++ AudioDubB, BlankClip(A)) # insert silent audio with same format

# Open a YV12 video where the width is not a multiple of four
Avisource("D:\Projects\test.avi", pixel_type="+YV12")

# opens the first video and second audio stream of a clip
AviSource("D:\Projects\test_multi10.avi", vtrack=0, atrack=1)

Changes