Fix compile errors and warnings, update readme

README.md

@@ -1,6 +1,22 @@
+
 # psxavenc
 
-psxavenc is an open-source command-line tool allowing for the encoding of PS1-format audio and video data.
+psxavenc is an open-source command-line tool for encoding audio and video data
+into formats commonly used on the original PlayStation.
+
+## Installation
+
+Requirements:
+
+- a recent version of FFmpeg libraries (`libavformat`, `libavcodec`,
+  `libavutil`, `libswresample`, `libswscale`);
+- a recent version of Meson.
+
+```shell
+$ meson setup build
+$ cd build
+$ ninja install
+```
 
 ## Usage
 
@@ -8,21 +24,49 @@ Run `psxavenc`.
 
 ### Examples
 
-Converting a sound file to a 22050Hz SPU sample:
+Rescale a video file to ≤320x240 pixels (preserving aspect ratio) and encode it
+into a 15fps .STR file with 37800 Hz 4-bit stereo audio and 2352-byte sectors,
+meant to be played at 2x CD-ROM speed:
 
 ```shell
-$ psxavenc -f 22050 -t spu -c 1 -b 4 sound_file.ogg sound_file.snd
+$ psxavenc -t str2cd -f 37800 -b 4 -c 2 -s 320x240 -r 15 -x 2 in.mp4 out.str
 ```
 
-## Installation
-
-Requirements:
-
-* a recent version of FFmpeg,
-* a recent version of Meson.
+Convert a mono audio sample to 22050 Hz raw SPU-ADPCM data:
 
 ```shell
-$ meson setup build
-$ cd build
-$ ninja install
+$ psxavenc -t spu -f 22050 in.ogg out.snd
 ```
+
+Convert a stereo audio file to a 44100 Hz interleaved .VAG file with 8192-byte
+interleave and loop flags set at the end of each interleaved chunk:
+
+```shell
+$ psxavenc -t vagi -f 44100 -c 2 -L -i 8192 in.wav out.vag
+```
+
+## Supported formats
+
+| Format   | Audio            | Channels | Video | Sector size |
+| :------- | :--------------- | :------- | :---- | :---------- |
+| `xa`     | XA-ADPCM         | 1 or 2   | None  | 2336 bytes  |
+| `xacd`   | XA-ADPCM         | 1 or 2   | None  | 2352 bytes  |
+| `spu`    | SPU-ADPCM        | 1        | None  |             |
+| `spui`   | SPU-ADPCM        | Any      | None  | Any         |
+| `vag`    | SPU-ADPCM        | 1        | None  |             |
+| `vagi`   | SPU-ADPCM        | Any      | None  | Any         |
+| `str2`   | None or XA-ADPCM | 1 or 2   | BS v2 | 2336 bytes  |
+| `str2cd` | None or XA-ADPCM | 1 or 2   | BS v2 | 2352 bytes  |
+| `sbs2`   | None             |          | BS v2 | Any         |
+
+Notes:
+
+- `vag` and `vagi` are similar to `spu` and `spui` respectively, but add a .VAG
+  header at the beginning of the file. The header is always 48 bytes long for
+  `vag` files, while in the case of `vagi` files it is padded to the size
+  specified using the `-a` option (2048 bytes by default). Note that `vagi`
+  files with more than 2 channels and/or alignment other than 2048 bytes are not
+  standardized.
+- The `sbs2` format (used in some System 573 games) is simply a series of
+  concatenated BS v2 frames, each padded to the size specified by the `-a`
+  option, with no additional headers besides the BS frame headers.