decoder/ffmpeg: skip unwanted samples after seeking
When seeking to the beginning of a packet, skip the samples that come before the desired time stamp.
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2
NEWS
2
NEWS
@ -2,6 +2,8 @@ ver 0.19.10 (not yet released)
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* input
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* input
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- curl: fix deadlock on small responses
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- curl: fix deadlock on small responses
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- smbclient: fix DFF playback
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- smbclient: fix DFF playback
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* decoder
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- ffmpeg: improve seeking accuracy
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* encoder
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* encoder
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- opus: fix bogus granulepos
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- opus: fix bogus granulepos
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* neighbor
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* neighbor
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@ -321,18 +321,44 @@ StreamRelativePts(const AVPacket &packet, const AVStream &stream)
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return pts - start;
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return pts - start;
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}
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}
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/**
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* Convert a non-negative stream-relative time stamp in
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* AVStream::time_base units to a PCM frame number.
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*/
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gcc_pure
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static uint64_t
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PtsToPcmFrame(uint64_t pts, const AVStream &stream,
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const AVCodecContext &codec_context)
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{
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return av_rescale_q(pts, stream.time_base, codec_context.time_base);
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}
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/**
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* @param min_frame skip all data before this PCM frame number; this
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* is used after seeking to skip data in an AVPacket until the exact
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* desired time stamp has been reached
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*/
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static DecoderCommand
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static DecoderCommand
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ffmpeg_send_packet(Decoder &decoder, InputStream &is,
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ffmpeg_send_packet(Decoder &decoder, InputStream &is,
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const AVPacket *packet,
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const AVPacket *packet,
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AVCodecContext *codec_context,
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AVCodecContext *codec_context,
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const AVStream *stream,
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const AVStream *stream,
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AVFrame *frame,
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AVFrame *frame,
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uint64_t min_frame, size_t pcm_frame_size,
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uint8_t **buffer, int *buffer_size)
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uint8_t **buffer, int *buffer_size)
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{
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{
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size_t skip_bytes = 0;
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const auto pts = StreamRelativePts(*packet, *stream);
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const auto pts = StreamRelativePts(*packet, *stream);
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if (pts >= 0) {
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if (pts >= 0) {
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decoder_timestamp(decoder,
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if (min_frame > 0) {
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time_from_ffmpeg(pts, stream->time_base));
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auto cur_frame = PtsToPcmFrame(pts, *stream,
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*codec_context);
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if (cur_frame < min_frame)
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skip_bytes = pcm_frame_size * (min_frame - cur_frame);
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} else
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decoder_timestamp(decoder,
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time_from_ffmpeg(pts, stream->time_base));
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}
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}
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AVPacket packet2 = *packet;
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AVPacket packet2 = *packet;
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@ -368,8 +394,20 @@ ffmpeg_send_packet(Decoder &decoder, InputStream &is,
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if (audio_size <= 0)
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if (audio_size <= 0)
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continue;
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continue;
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const uint8_t *data = output_buffer;
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if (skip_bytes > 0) {
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if (skip_bytes >= size_t(audio_size)) {
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skip_bytes -= audio_size;
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continue;
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}
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data += skip_bytes;
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audio_size -= skip_bytes;
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skip_bytes = 0;
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}
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cmd = decoder_data(decoder, is,
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cmd = decoder_data(decoder, is,
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output_buffer, audio_size,
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data, audio_size,
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codec_context->bit_rate / 1000);
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codec_context->bit_rate / 1000);
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}
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}
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return cmd;
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return cmd;
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@ -573,6 +611,8 @@ ffmpeg_decode(Decoder &decoder, InputStream &input)
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uint8_t *interleaved_buffer = nullptr;
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uint8_t *interleaved_buffer = nullptr;
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int interleaved_buffer_size = 0;
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int interleaved_buffer_size = 0;
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uint64_t min_frame = 0;
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DecoderCommand cmd;
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DecoderCommand cmd;
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do {
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do {
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AVPacket packet;
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AVPacket packet;
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@ -580,13 +620,15 @@ ffmpeg_decode(Decoder &decoder, InputStream &input)
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/* end of file */
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/* end of file */
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break;
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break;
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if (packet.stream_index == audio_stream)
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if (packet.stream_index == audio_stream) {
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cmd = ffmpeg_send_packet(decoder, input,
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cmd = ffmpeg_send_packet(decoder, input,
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&packet, codec_context,
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&packet, codec_context,
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av_stream,
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av_stream,
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frame,
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frame,
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min_frame, audio_format.GetFrameSize(),
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&interleaved_buffer, &interleaved_buffer_size);
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&interleaved_buffer, &interleaved_buffer_size);
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else
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min_frame = 0;
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} else
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cmd = decoder_get_command(decoder);
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cmd = decoder_get_command(decoder);
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av_free_packet(&packet);
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av_free_packet(&packet);
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@ -606,6 +648,7 @@ ffmpeg_decode(Decoder &decoder, InputStream &input)
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decoder_seek_error(decoder);
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decoder_seek_error(decoder);
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else {
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else {
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avcodec_flush_buffers(codec_context);
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avcodec_flush_buffers(codec_context);
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min_frame = decoder_seek_where_frame(decoder);
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decoder_command_finished(decoder);
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decoder_command_finished(decoder);
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}
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}
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}
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}
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