Added reader

pkg/ffmpeg/opts.go

@@ -22,6 +22,10 @@ type opts struct {
 	oformat  *ffmpeg.AVOutputFormat
 	streams  map[int]*Par
 	metadata []*Metadata
+
+	// Reader options
+	iformat *ffmpeg.AVInputFormat
+	opts    []string // These are key=value pairs
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -50,6 +54,27 @@ func OptOutputFormat(name string) Opt {
 	}
 }
 
+// Input format from name or url
+func OptInputFormat(name string) Opt {
+	return func(o *opts) error {
+		// By name
+		if iformat := ffmpeg.AVFormat_find_input_format(name); iformat != nil {
+			o.iformat = iformat
+		} else {
+			return ErrBadParameter.Withf("invalid input format %q", name)
+		}
+		return nil
+	}
+}
+
+// Input format options
+func OptInputOpt(opt ...string) Opt {
+	return func(o *opts) error {
+		o.opts = append(o.opts, opt...)
+		return nil
+	}
+}
+
 // New stream with parameters
 func OptStream(stream int, par *Par) Opt {
 	return func(o *opts) error {

pkg/ffmpeg/reader.go

@@ -0,0 +1,223 @@
+package ffmpeg
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"slices"
+	"strings"
+	"time"
+
+	// Packages
+	ff "github.com/mutablelogic/go-media/sys/ffmpeg61"
+)
+
+////////////////////////////////////////////////////////////////////////////////
+// TYPES
+
+// Media reader which reads from a URL, file path or device
+type Reader struct {
+	input *ff.AVFormatContext
+	avio  *ff.AVIOContextEx
+}
+
+type reader_callback struct {
+	r io.Reader
+}
+
+// Return parameters if a stream should be decoded and either resampled or
+// resized. Return nil if you want to ignore the stream, or pass back the
+// stream parameters if you want to copy the stream without any changes.
+type DecoderMapFunc func(int, *Par) (*Par, error)
+
+////////////////////////////////////////////////////////////////////////////////
+// LIFECYCLE
+
+// Open media from a url, file path or device
+func Open(url string, opt ...Opt) (*Reader, error) {
+	options := newOpts()
+	reader := new(Reader)
+
+	// Apply options
+	for _, opt := range opt {
+		if err := opt(options); err != nil {
+			return nil, err
+		}
+	}
+
+	// Get the options
+	dict := ff.AVUtil_dict_alloc()
+	defer ff.AVUtil_dict_free(dict)
+	if len(options.opts) > 0 {
+		if err := ff.AVUtil_dict_parse_string(dict, strings.Join(options.opts, " "), "=", " ", 0); err != nil {
+			return nil, err
+		}
+	}
+
+	// Open the device or stream
+	if ctx, err := ff.AVFormat_open_url(url, options.iformat, dict); err != nil {
+		return nil, err
+	} else {
+		reader.input = ctx
+	}
+
+	// Find stream information and do rest of the initialization
+	return reader.open(options)
+}
+
+// Create a new reader from an io.Reader
+func NewReader(r io.Reader, opt ...Opt) (*Reader, error) {
+	options := newOpts()
+	reader := new(Reader)
+
+	// Apply options
+	for _, opt := range opt {
+		if err := opt(options); err != nil {
+			return nil, err
+		}
+	}
+
+	// Get the options
+	dict := ff.AVUtil_dict_alloc()
+	defer ff.AVUtil_dict_free(dict)
+	if len(options.opts) > 0 {
+		if err := ff.AVUtil_dict_parse_string(dict, strings.Join(options.opts, " "), "=", " ", 0); err != nil {
+			return nil, err
+		}
+	}
+
+	// Allocate the AVIO context
+	reader.avio = ff.AVFormat_avio_alloc_context(bufSize, false, &reader_callback{r})
+	if reader.avio == nil {
+		return nil, errors.New("failed to allocate avio context")
+	}
+
+	// Open the stream
+	if ctx, err := ff.AVFormat_open_reader(reader.avio, options.iformat, dict); err != nil {
+		ff.AVFormat_avio_context_free(reader.avio)
+		return nil, err
+	} else {
+		reader.input = ctx
+	}
+
+	// Find stream information and do rest of the initialization
+	return reader.open(options)
+}
+
+func (r *Reader) open(_ *opts) (*Reader, error) {
+	// Find stream information
+	if err := ff.AVFormat_find_stream_info(r.input, nil); err != nil {
+		ff.AVFormat_free_context(r.input)
+		ff.AVFormat_avio_context_free(r.avio)
+		return nil, err
+	}
+
+	// Return success
+	return r, nil
+}
+
+// Close the reader
+func (r *Reader) Close() error {
+	var result error
+
+	// Free resources
+	ff.AVFormat_free_context(r.input)
+	if r.avio != nil {
+		ff.AVFormat_avio_context_free(r.avio)
+	}
+
+	// Release resources
+	r.input = nil
+	r.avio = nil
+
+	// Return any errors
+	return result
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// STRINGIFY
+
+// Display the reader as a string
+func (r *Reader) MarshalJSON() ([]byte, error) {
+	return json.Marshal(r.input)
+}
+
+// Display the reader as a string
+func (r *Reader) String() string {
+	data, _ := json.MarshalIndent(r, "", "  ")
+	return string(data)
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// PUBLIC METHODS
+
+// Return the duration of the media stream, returns zero if unknown
+func (r *Reader) Duration() time.Duration {
+	duration := r.input.Duration()
+	if duration > 0 {
+		return time.Duration(duration) * time.Second / time.Duration(ff.AV_TIME_BASE)
+	}
+	return 0
+}
+
+// Return the metadata for the media stream, filtering by the specified keys
+// if there are any. Artwork is returned with the "artwork" key.
+func (r *Reader) Metadata(keys ...string) []*Metadata {
+	entries := ff.AVUtil_dict_entries(r.input.Metadata())
+	result := make([]*Metadata, 0, len(entries))
+	for _, entry := range entries {
+		if len(keys) == 0 || slices.Contains(keys, entry.Key()) {
+			result = append(result, NewMetadata(entry.Key(), entry.Value()))
+		}
+	}
+
+	// Obtain any artwork from the streams
+	if slices.Contains(keys, MetaArtwork) {
+		for _, stream := range r.input.Streams() {
+			if packet := stream.AttachedPic(); packet != nil {
+				result = append(result, NewMetadata(MetaArtwork, packet.Bytes()))
+			}
+		}
+	}
+
+	// Return all the metadata
+	return result
+}
+
+// TODO Decode the media stream into packets and frames
+func (r *Reader) Decode(ctx context.Context, fn DecoderMapFunc) error {
+	return errors.New("not implemented yet")
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// PRIVATE METHODS
+
+func (r *reader_callback) Reader(buf []byte) int {
+	n, err := r.r.Read(buf)
+	if err != nil {
+		return ff.AVERROR_EOF
+	}
+	return n
+}
+
+func (r *reader_callback) Seeker(offset int64, whence int) int64 {
+	whence = whence & ^ff.AVSEEK_FORCE
+	seeker, ok := r.r.(io.ReadSeeker)
+	if !ok {
+		return -1
+	}
+	switch whence {
+	case io.SeekStart, io.SeekCurrent, io.SeekEnd:
+		n, err := seeker.Seek(offset, whence)
+		if err != nil {
+			return -1
+		}
+		return n
+	}
+	return -1
+}
+
+func (r *reader_callback) Writer([]byte) int {
+	return ff.AVERROR_EOF
+}

pkg/ffmpeg/reader_test.go

@@ -0,0 +1,41 @@
+package ffmpeg_test
+
+import (
+	"os"
+	"testing"
+
+	ffmpeg "github.com/mutablelogic/go-media/pkg/ffmpeg"
+	assert "github.com/stretchr/testify/assert"
+)
+
+func Test_reader_001(t *testing.T) {
+	assert := assert.New(t)
+
+	// Read a file
+	r, err := ffmpeg.Open("../../etc/test/sample.mp4")
+	if !assert.NoError(err) {
+		t.FailNow()
+	}
+	defer r.Close()
+
+	t.Log(r)
+}
+
+func Test_reader_002(t *testing.T) {
+	assert := assert.New(t)
+
+	// Read a file
+	r, err := os.Open("../../etc/test/sample.mp4")
+	if !assert.NoError(err) {
+		t.FailNow()
+	}
+	defer r.Close()
+
+	media, err := ffmpeg.NewReader(r)
+	if !assert.NoError(err) {
+		t.FailNow()
+	}
+	defer media.Close()
+
+	t.Log(media)
+}

pkg/ffmpeg/writer.go

@@ -1,6 +1,7 @@
 package ffmpeg
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -191,6 +192,20 @@ func (w *Writer) Close() error {
 	return result
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// STRINGIFY
+
+// Display the writer as a string
+func (w *Writer) MarshalJSON() ([]byte, error) {
+	return json.Marshal(w.output)
+}
+
+// Display the writer as a string
+func (w *Writer) String() string {
+	data, _ := json.MarshalIndent(w, "", "  ")
+	return string(data)
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // PUBLIC METHODS