Fix MP4 audio bitrate

benches/read_file.rs

@@ -15,7 +15,7 @@ macro_rules! test_read_path {
 test_read_path!(read_aiff_path, "tests/files/assets/a.aiff");
 test_read_path!(read_ape_path, "tests/files/assets/a.ape");
 test_read_path!(read_flac_path, "tests/files/assets/a.flac");
-test_read_path!(read_m4a_path, "tests/files/assets/a.m4a");
+test_read_path!(read_m4a_path, "tests/files/assets/m4a_codec_aac.m4a");
 test_read_path!(read_mp3_path, "tests/files/assets/a.mp3");
 test_read_path!(read_vorbis_path, "tests/files/assets/a.ogg");
 test_read_path!(read_opus_path, "tests/files/assets/a.opus");
@@ -50,7 +50,11 @@ macro_rules! test_read_file {
 test_read_file!(read_aiff_file, AIFF, "../tests/files/assets/a.aiff");
 test_read_file!(read_ape_file, APE, "../tests/files/assets/a.ape");
 test_read_file!(read_flac_file, FLAC, "../tests/files/assets/a.flac");
-test_read_file!(read_m4a_file, MP4, "../tests/files/assets/a.m4a");
+test_read_file!(
+	read_m4a_file,
+	MP4,
+	"../tests/files/assets/m4a_codec_aac.m4a"
+);
 test_read_file!(read_mp3_file, MP3, "../tests/files/assets/a.mp3");
 test_read_file!(read_vorbis_file, VORBIS, "../tests/files/assets/a.ogg");
 test_read_file!(read_opus_file, OPUS, "../tests/files/assets/a.opus");

src/mp4/properties.rs

@@ -171,37 +171,37 @@ where
 		return Err(LoftyError::Mp4("File contains no audio tracks"));
 	}
 
-	let duration = match mdhd {
-		Some(mdhd) => {
-			data.seek(SeekFrom::Start(mdhd.start + 8))?;
-
-			let version = data.read_u8()?;
-			let _flags = data.read_uint::<BigEndian>(3)?;
-
-			let (timescale, duration) = if version == 1 {
-				// We don't care about these two values
-				let _creation_time = data.read_u64::<BigEndian>()?;
-				let _modification_time = data.read_u64::<BigEndian>()?;
-
-				let timescale = data.read_u32::<BigEndian>()?;
-				let duration = data.read_u64::<BigEndian>()?;
-
-				(timescale, duration)
-			} else {
-				let _creation_time = data.read_u32::<BigEndian>()?;
-				let _modification_time = data.read_u32::<BigEndian>()?;
-
-				let timescale = data.read_u32::<BigEndian>()?;
-				let duration = data.read_u32::<BigEndian>()?;
-
-				(timescale, u64::from(duration))
-			};
-
-			Duration::from_millis(duration * 1000 / u64::from(timescale))
-		},
+	let mdhd = match mdhd {
+		Some(mdhd) => mdhd,
 		None => return Err(LoftyError::BadAtom("Expected atom \"trak.mdia.mdhd\"")),
 	};
 
+	data.seek(SeekFrom::Start(mdhd.start + 8))?;
+
+	let version = data.read_u8()?;
+	let _flags = data.read_uint::<BigEndian>(3)?;
+
+	let (timescale, duration) = if version == 1 {
+		// We don't care about these two values
+		let _creation_time = data.read_u64::<BigEndian>()?;
+		let _modification_time = data.read_u64::<BigEndian>()?;
+
+		let timescale = data.read_u32::<BigEndian>()?;
+		let duration = data.read_u64::<BigEndian>()?;
+
+		(timescale, duration)
+	} else {
+		let _creation_time = data.read_u32::<BigEndian>()?;
+		let _modification_time = data.read_u32::<BigEndian>()?;
+
+		let timescale = data.read_u32::<BigEndian>()?;
+		let duration = data.read_u32::<BigEndian>()?;
+
+		(timescale, u64::from(duration))
+	};
+
+	let duration = Duration::from_millis(duration * 1000 / u64::from(timescale));
+
 	// We create the properties here, since it is possible the other information isn't available
 	let mut properties = Mp4Properties {
 		codec: Mp4Codec::Unknown(String::new()),
@@ -234,7 +234,7 @@ where
 				if let AtomIdent::Fourcc(ref fourcc) = atom.ident {
 					match fourcc {
 						b"mp4a" => mp4a_properties(&mut stsd_reader, &mut properties, file_length)?,
-						b"alac" => alac_properties(&mut stsd_reader, &mut properties)?,
+						b"alac" => alac_properties(&mut stsd_reader, &mut properties, file_length)?,
 						unknown => {
 							if let Ok(codec) = std::str::from_utf8(unknown) {
 								properties.codec = Mp4Codec::Unknown(codec.to_string())
@@ -323,7 +323,7 @@ where
 	Ok(())
 }
 
-fn alac_properties<R>(data: &mut R, properties: &mut Mp4Properties) -> Result<()>
+fn alac_properties<R>(data: &mut R, properties: &mut Mp4Properties, file_length: u64) -> Result<()>
 where
 	R: Read + Seek,
 {
@@ -352,7 +352,8 @@ where
 			data.seek(SeekFrom::Current(9))?;
 
 			// Sample size (1)
-			properties.bit_depth = Some(data.read_u8()?);
+			let sample_size = data.read_u8()?;
+			properties.bit_depth = Some(sample_size);
 
 			// Skipping 3 bytes
 			// Rice history mult (1)
@@ -367,7 +368,11 @@ where
 			// Max frame size (4)
 			data.seek(SeekFrom::Current(6))?;
 
-			properties.audio_bitrate = data.read_u32::<BigEndian>()?;
+			let overall_bitrate = u128::from(file_length * 8) / properties.duration.as_millis();
+			properties.overall_bitrate = overall_bitrate as u32;
+
+			// TODO: Determine bitrate from mdat
+			properties.audio_bitrate = data.read_u32::<BigEndian>()? / 1000;
 			properties.sample_rate = data.read_u32::<BigEndian>()?;
 		}
 	}

tests/files/mp4.rs

@@ -5,7 +5,7 @@ use std::io::{Seek, SeekFrom, Write};
 #[test]
 fn read() {
 	// This file contains an ilst atom
-	let file = lofty::read_from_path("tests/files/assets/a.m4a", false).unwrap();
+	let file = lofty::read_from_path("tests/files/assets/m4a_codec_aac.m4a", false).unwrap();
 
 	assert_eq!(file.file_type(), &FileType::MP4);
 
@@ -15,7 +15,7 @@ fn read() {
 
 #[test]
 fn write() {
-	let mut file = temp_file!("tests/files/assets/a.m4a");
+	let mut file = temp_file!("tests/files/assets/m4a_codec_aac.m4a");
 
 	let mut tagged_file = lofty::read_from(&mut file, false).unwrap();
 
@@ -33,5 +33,5 @@ fn write() {
 
 #[test]
 fn remove() {
-	crate::remove_tag!("tests/files/assets/a.m4a", TagType::Mp4Ilst);
+	crate::remove_tag!("tests/files/assets/m4a_codec_aac.m4a", TagType::Mp4Ilst);
 }

tests/properties.rs

@@ -40,7 +40,7 @@ const MP3_PROPERTIES: Mp3Properties = Mp3Properties::new(
 	2,
 );
 
-const MP4_PROPERTIES: Mp4Properties = Mp4Properties::new(
+const MP4_AAC_PROPERTIES: Mp4Properties = Mp4Properties::new(
 	Mp4Codec::AAC,
 	Duration::from_millis(1449),
 	135,
@@ -50,11 +50,11 @@ const MP4_PROPERTIES: Mp4Properties = Mp4Properties::new(
 	2,
 );
 
-const ALAC_PROPERTIES: Mp4Properties = Mp4Properties::new(
+const MP4_ALAC_PROPERTIES: Mp4Properties = Mp4Properties::new(
 	Mp4Codec::ALAC,
 	Duration::from_millis(1428),
 	331,
-	124,
+	1536,
 	48000,
 	Some(16),
 	2,
@@ -130,18 +130,18 @@ fn mp3_properties() {
 }
 
 #[test]
-fn mp4_properties() {
+fn mp4_aac_properties() {
 	assert_eq!(
-		get_properties::<Mp4File>("tests/files/assets/a.m4a"),
-		MP4_PROPERTIES
+		get_properties::<Mp4File>("tests/files/assets/m4a_codec_aac.m4a"),
+		MP4_AAC_PROPERTIES
 	)
 }
 
 #[test]
-fn alac_properties() {
+fn mp4_alac_properties() {
 	assert_eq!(
-		get_properties::<Mp4File>("tests/files/assets/b.m4a").bit_depth(),
-		ALAC_PROPERTIES.bit_depth()
+		get_properties::<Mp4File>("tests/files/assets/m4a_codec_alac.m4a"),
+		MP4_ALAC_PROPERTIES
 	)
 }