init

src/main.rs

@@ -0,0 +1,209 @@
+extern crate ffmpeg;
+
+use std::env;
+use std::path::Path;
+
+use ffmpeg::{codec, filter, format, frame, media};
+use ffmpeg::{rescale, Rescale};
+
+fn filter(
+    decoder: &codec::decoder::Audio,
+    encoder: &codec::encoder::Audio,
+) -> Result<filter::Graph, ffmpeg::Error> {
+    let mut filter = filter::Graph::new();
+
+    let args = format!(
+        "time_base={}:sample_rate={}:sample_fmt={}:channel_layout=0x{:x}",
+        decoder.time_base(),
+        decoder.rate(),
+        decoder.format().name(),
+        decoder.channel_layout().bits()
+    );
+
+    filter.add(&filter::find("abuffer").unwrap(), "in", &args)?;
+    filter.add(&filter::find("abuffersink").unwrap(), "out", "")?;
+
+    {
+        let mut out = filter.get("out").unwrap();
+
+        out.set_sample_format(encoder.format());
+        out.set_channel_layout(encoder.channel_layout());
+        out.set_sample_rate(encoder.rate());
+    }
+
+    filter.output("in", 0)?.input("out", 0)?.parse("anull")?;
+    filter.validate()?;
+
+    println!("{}", filter.dump());
+
+    if let Some(codec) = encoder.codec() {
+        if !codec
+            .capabilities()
+            .contains(ffmpeg::codec::capabilities::VARIABLE_FRAME_SIZE)
+        {
+            filter
+                .get("out")
+                .unwrap()
+                .sink()
+                .set_frame_size(encoder.frame_size());
+        }
+    }
+
+    Ok(filter)
+}
+
+struct Transcoder {
+    stream: usize,
+    filter: filter::Graph,
+    decoder: codec::decoder::Audio,
+    encoder: codec::encoder::Audio,
+}
+
+fn transcoder<P: AsRef<Path>>(
+    ictx: &mut format::context::Input,
+    octx: &mut format::context::Output,
+    path: &P,
+) -> Result<Transcoder, ffmpeg::Error> {
+    let input = ictx
+        .streams()
+        .best(media::Type::Audio)
+        .expect("could not find best audio stream");
+    let mut decoder = input.codec().decoder().audio()?;
+    let codec = ffmpeg::encoder::find(octx.format().codec(path, media::Type::Audio))
+        .expect("failed to find encoder")
+        .audio()?;
+    let global = octx
+        .format()
+        .flags()
+        .contains(ffmpeg::format::flag::GLOBAL_HEADER);
+
+    decoder.set_parameters(input.parameters())?;
+
+    let mut output = octx.add_stream(codec)?;
+    let mut encoder = output.codec().encoder().audio()?;
+
+    let channel_layout = codec
+        .channel_layouts()
+        .map(|cls| cls.best(decoder.channel_layout().channels()))
+        .unwrap_or(ffmpeg::channel_layout::STEREO);
+
+    if global {
+        encoder.set_flags(ffmpeg::codec::flag::GLOBAL_HEADER);
+    }
+
+    encoder.set_rate(48_000); //decoder.rate() as i32);
+    encoder.set_channel_layout(channel_layout);
+    encoder.set_channels(channel_layout.channels());
+    encoder.set_format(
+        codec
+            .formats()
+            .expect("unknown supported formats")
+            .next()
+            .unwrap(),
+    );
+    encoder.set_bit_rate(decoder.bit_rate());
+    encoder.set_max_bit_rate(decoder.max_bit_rate());
+
+    encoder.set_time_base((1, decoder.rate() as i32));
+    output.set_time_base((1, decoder.rate() as i32));
+
+    let encoder = encoder.open_as(codec)?;
+    output.set_parameters(&encoder);
+
+    let filter = filter(&decoder, &encoder)?;
+
+    Ok(Transcoder {
+        stream: input.index(),
+        filter: filter,
+        decoder: decoder,
+        encoder: encoder,
+    })
+}
+
+// Transcode the `best` audio stream of the input file into a the output file while applying a
+// given filter. If no filter was specified the stream gets copied (`anull` filter).
+//
+// Example 1: Transcode *.mp3 file to *.wmv while speeding it up
+// transcode-audio in.mp3 out.wmv "atempo=1.2"
+//
+// Example 2: Overlay an audio file
+// transcode-audio in.mp3 out.mp3 "amovie=overlay.mp3 [ov]; [in][ov] amerge [out]"
+//
+// Example 3: Seek to a specified position (in seconds)
+// transcode-audio in.mp3 out.mp3 anull 30
+fn main() -> Result<(), ffmpeg::Error> {
+    ffmpeg::init()?;
+
+    let input = env::args().nth(1).expect("missing input");
+    let output = env::args().nth(2).expect("missing output");
+
+    let mut ictx = format::input(&input)?;
+    let mut octx = format::output(&output)?;
+    let mut transcoder = transcoder(&mut ictx, &mut octx, &output)?;
+
+    octx.set_metadata(ictx.metadata().to_owned());
+    octx.write_header()?;
+
+    let in_time_base = transcoder.decoder.time_base();
+    let out_time_base = octx.stream(0).unwrap().time_base();
+
+    let mut decoded = frame::Audio::empty();
+    let mut encoded = ffmpeg::Packet::empty();
+
+    for (stream, mut packet) in ictx.packets() {
+        if stream.index() == transcoder.stream {
+            packet.rescale_ts(stream.time_base(), in_time_base);
+
+            if let Ok(true) = transcoder.decoder.decode(&packet, &mut decoded) {
+                // let timestamp = decoded.timestamp();
+                // decoded.set_pts(timestamp);
+
+                transcoder
+                    .filter
+                    .get("in")
+                    .unwrap()
+                    .source()
+                    .add(&decoded)?;
+
+                while let Ok(..) = transcoder
+                    .filter
+                    .get("out")
+                    .unwrap()
+                    .sink()
+                    .frame(&mut decoded)
+                {
+                    if let Ok(true) = transcoder.encoder.encode(&decoded, &mut encoded) {
+                        encoded.set_stream(0);
+                        encoded.rescale_ts(in_time_base, out_time_base);
+                        encoded.write_interleaved(&mut octx)?;
+                    }
+                }
+            }
+        }
+    }
+
+    transcoder.filter.get("in").unwrap().source().flush()?;
+
+    while let Ok(..) = transcoder
+        .filter
+        .get("out")
+        .unwrap()
+        .sink()
+        .frame(&mut decoded)
+    {
+        if let Ok(true) = transcoder.encoder.encode(&decoded, &mut encoded) {
+            encoded.set_stream(0);
+            encoded.rescale_ts(in_time_base, out_time_base);
+            encoded.write_interleaved(&mut octx)?;
+        }
+    }
+
+    if let Ok(true) = transcoder.encoder.flush(&mut encoded) {
+        encoded.set_stream(0);
+        encoded.rescale_ts(in_time_base, out_time_base);
+        encoded.write_interleaved(&mut octx)?;
+    }
+
+    octx.write_trailer()?;
+    Ok(())
+}