From f768ca3a2d20cc839e25ca3c95438909d54afd77 Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Fri, 19 Jun 2015 18:56:29 +0200 Subject: decoder/ffmpeg: move code to StreamRelativePts() --- src/decoder/plugins/FfmpegDecoderPlugin.cxx | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) (limited to 'src/decoder/plugins') diff --git a/src/decoder/plugins/FfmpegDecoderPlugin.cxx b/src/decoder/plugins/FfmpegDecoderPlugin.cxx index 722f954e2..586a1ef41 100644 --- a/src/decoder/plugins/FfmpegDecoderPlugin.cxx +++ b/src/decoder/plugins/FfmpegDecoderPlugin.cxx @@ -305,6 +305,22 @@ copy_interleave_frame(const AVCodecContext *codec_context, return data_size; } +/** + * Convert AVPacket::pts to a stream-relative time stamp (still in + * AVStream::time_base units). Returns a negative value on error. + */ +gcc_pure +static int64_t +StreamRelativePts(const AVPacket &packet, const AVStream &stream) +{ + auto pts = packet.pts; + if (pts < 0 || pts == int64_t(AV_NOPTS_VALUE)) + return -1; + + auto start = start_time_fallback(stream); + return pts - start; +} + static DecoderCommand ffmpeg_send_packet(Decoder &decoder, InputStream &is, const AVPacket *packet, @@ -313,12 +329,10 @@ ffmpeg_send_packet(Decoder &decoder, InputStream &is, AVFrame *frame, uint8_t **buffer, int *buffer_size) { - if (packet->pts >= 0 && packet->pts != (int64_t)AV_NOPTS_VALUE) { - auto start = start_time_fallback(*stream); - if (packet->pts >= start) - decoder_timestamp(decoder, - time_from_ffmpeg(packet->pts - start, - stream->time_base)); + const auto pts = StreamRelativePts(*packet, *stream); + if (pts >= 0) { + decoder_timestamp(decoder, + time_from_ffmpeg(pts, stream->time_base)); } AVPacket packet2 = *packet; -- cgit v1.2.3 From d11e2724c4f1dbe3447b3e81d0a0e71bcc504a0b Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Fri, 19 Jun 2015 17:45:05 +0200 Subject: decoder/ffmpeg: use AVSEEK_FLAG_BACKWARD for seeking Ask FFmpeg to seek to the next packet boundary *before* the seek position, so we don't miss audio data. Now we get too much, but we'll solve that in the next commit. --- src/decoder/plugins/FfmpegDecoderPlugin.cxx | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'src/decoder/plugins') diff --git a/src/decoder/plugins/FfmpegDecoderPlugin.cxx b/src/decoder/plugins/FfmpegDecoderPlugin.cxx index 586a1ef41..f5c0e0a36 100644 --- a/src/decoder/plugins/FfmpegDecoderPlugin.cxx +++ b/src/decoder/plugins/FfmpegDecoderPlugin.cxx @@ -597,8 +597,12 @@ ffmpeg_decode(Decoder &decoder, InputStream &input) av_stream->time_base) + start_time_fallback(*av_stream); + /* AVSEEK_FLAG_BACKWARD asks FFmpeg to seek to + the packet boundary before the seek time + stamp, not after */ + if (av_seek_frame(format_context, audio_stream, where, - AVSEEK_FLAG_ANY) < 0) + AVSEEK_FLAG_ANY|AVSEEK_FLAG_BACKWARD) < 0) decoder_seek_error(decoder); else { avcodec_flush_buffers(codec_context); -- cgit v1.2.3 From 327a8e6c5974f99ff1067afc2e725a2ebc2c4802 Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Fri, 19 Jun 2015 18:02:10 +0200 Subject: 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. --- src/decoder/plugins/FfmpegDecoderPlugin.cxx | 53 ++++++++++++++++++++++++++--- 1 file changed, 48 insertions(+), 5 deletions(-) (limited to 'src/decoder/plugins') 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); } } -- cgit v1.2.3