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-rw-r--r--src/decoder/plugins/FfmpegDecoderPlugin.cxx53
1 files changed, 48 insertions, 5 deletions
diff --git a/src/decoder/plugins/FfmpegDecoderPlugin.cxx b/src/decoder/plugins/FfmpegDecoderPlugin.cxx
index f5c0e0a36..d5191a3c3 100644
--- a/src/decoder/plugins/FfmpegDecoderPlugin.cxx
+++ b/src/decoder/plugins/FfmpegDecoderPlugin.cxx
@@ -321,18 +321,44 @@ StreamRelativePts(const AVPacket &packet, const AVStream &stream)
return pts - start;
}
+/**
+ * Convert a non-negative stream-relative time stamp in
+ * AVStream::time_base units to a PCM frame number.
+ */
+gcc_pure
+static uint64_t
+PtsToPcmFrame(uint64_t pts, const AVStream &stream,
+ const AVCodecContext &codec_context)
+{
+ return av_rescale_q(pts, stream.time_base, codec_context.time_base);
+}
+
+/**
+ * @param min_frame skip all data before this PCM frame number; this
+ * is used after seeking to skip data in an AVPacket until the exact
+ * desired time stamp has been reached
+ */
static DecoderCommand
ffmpeg_send_packet(Decoder &decoder, InputStream &is,
const AVPacket *packet,
AVCodecContext *codec_context,
const AVStream *stream,
AVFrame *frame,
+ uint64_t min_frame, size_t pcm_frame_size,
uint8_t **buffer, int *buffer_size)
{
+ size_t skip_bytes = 0;
+
const auto pts = StreamRelativePts(*packet, *stream);
if (pts >= 0) {
- decoder_timestamp(decoder,
- time_from_ffmpeg(pts, stream->time_base));
+ if (min_frame > 0) {
+ auto cur_frame = PtsToPcmFrame(pts, *stream,
+ *codec_context);
+ if (cur_frame < min_frame)
+ skip_bytes = pcm_frame_size * (min_frame - cur_frame);
+ } else
+ decoder_timestamp(decoder,
+ time_from_ffmpeg(pts, stream->time_base));
}
AVPacket packet2 = *packet;
@@ -368,8 +394,20 @@ ffmpeg_send_packet(Decoder &decoder, InputStream &is,
if (audio_size <= 0)
continue;
+ const uint8_t *data = output_buffer;
+ if (skip_bytes > 0) {
+ if (skip_bytes >= size_t(audio_size)) {
+ skip_bytes -= audio_size;
+ continue;
+ }
+
+ data += skip_bytes;
+ audio_size -= skip_bytes;
+ skip_bytes = 0;
+ }
+
cmd = decoder_data(decoder, is,
- output_buffer, audio_size,
+ data, audio_size,
codec_context->bit_rate / 1000);
}
return cmd;
@@ -573,6 +611,8 @@ ffmpeg_decode(Decoder &decoder, InputStream &input)
uint8_t *interleaved_buffer = nullptr;
int interleaved_buffer_size = 0;
+ uint64_t min_frame = 0;
+
DecoderCommand cmd;
do {
AVPacket packet;
@@ -580,13 +620,15 @@ ffmpeg_decode(Decoder &decoder, InputStream &input)
/* end of file */
break;
- if (packet.stream_index == audio_stream)
+ if (packet.stream_index == audio_stream) {
cmd = ffmpeg_send_packet(decoder, input,
&packet, codec_context,
av_stream,
frame,
+ min_frame, audio_format.GetFrameSize(),
&interleaved_buffer, &interleaved_buffer_size);
- else
+ min_frame = 0;
+ } else
cmd = decoder_get_command(decoder);
av_free_packet(&packet);
@@ -606,6 +648,7 @@ ffmpeg_decode(Decoder &decoder, InputStream &input)
decoder_seek_error(decoder);
else {
avcodec_flush_buffers(codec_context);
+ min_frame = decoder_seek_where_frame(decoder);
decoder_command_finished(decoder);
}
}