我想重新采样mkv（vp8 / ogg）以及原始4位adpcm到原始16位pcm byte []以从xna库加载到SoundEffect中。所以当我使用其他代码显示帧时（视频端正在工作），我可以播放它。我可以读取一个16位的wav文件并播放它。但是，当我转到重新采样时，它不会100％播放。一个文件是3分钟和15秒。退出前我只有13秒和739毫秒。我一直在学习如何通过在c ++中查找代码示例并使用ffmpeg.autogen将其更正为c＃来工作。
以下是我重新取样的最佳尝试。
int nb_samples = Frame->nb_samples;
int output_nb_samples = nb_samples;
int nb_channels = ffmpeg.av_get_channel_layout_nb_channels(ffmpeg.AV_CH_LAYOUT_STEREO);
int bytes_per_sample = ffmpeg.av_get_bytes_per_sample(AVSampleFormat.AV_SAMPLE_FMT_S16) * nb_channels;
int bufsize = ffmpeg.av_samples_get_buffer_size(null, nb_channels, nb_samples,
AVSampleFormat.AV_SAMPLE_FMT_S16, 1);
byte*[] b = Frame->data;
fixed (byte** input = b)
{
byte* output = null;
ffmpeg.av_samples_alloc(&output, null,
nb_channels,
nb_samples,
(AVSampleFormat)Frame->format, 0);//
// Buffer input
Ret = ffmpeg.swr_convert(Swr, &output, output_nb_samples / 2, input, nb_samples);
CheckRet();
WritetoMs(output, 0, Ret * bytes_per_sample);
output_nb_samples -= Ret;
// Drain buffer
while ((Ret = ffmpeg.swr_convert(Swr, &output, output_nb_samples, null, 0)) > 0)
{
CheckRet();
WritetoMs(output, 0, Ret * bytes_per_sample);
output_nb_samples -= Ret;
}
}
我改变了这一切，但它很快就切断了。
Channels = ffmpeg.av_get_channel_layout_nb_channels(OutFrame->channel_layout);
int nb_channels = ffmpeg.av_get_channel_layout_nb_channels(ffmpeg.AV_CH_LAYOUT_STEREO);
int bytes_per_sample = ffmpeg.av_get_bytes_per_sample(AVSampleFormat.AV_SAMPLE_FMT_S16) * nb_channels;
if((Ret = ffmpeg.swr_convert_frame(Swr, OutFrame, Frame))>=0)
WritetoMs(*OutFrame->extended_data, 0, OutFrame->nb_samples * bytes_per_sample);
CheckRet();
两个代码都使用一个函数来设置Swr，它在第一帧被解码后运行一次。
private void PrepareResampler()
{
ffmpeg.av_frame_copy_props(OutFrame, Frame);
OutFrame->channel_layout = ffmpeg.AV_CH_LAYOUT_STEREO;
OutFrame->format = (int)AVSampleFormat.AV_SAMPLE_FMT_S16;
OutFrame->sample_rate = Frame->sample_rate;
OutFrame->channels = 2;
Swr = ffmpeg.swr_alloc();
if (Swr == null)
throw new Exception("SWR = Null");
Ret = ffmpeg.swr_config_frame(Swr, OutFrame, Frame);
CheckRet();
Ret = ffmpeg.swr_init(Swr);
CheckRet();
Ret = ffmpeg.swr_is_initialized(Swr);
CheckRet();
}
这是我获取输出并将其置于声音效果中的位置
private void ReadAll()
{
using (Ms = new MemoryStream())
{
while (true)
{
Ret = ffmpeg.av_read_frame(Format, Packet);
if (Ret == ffmpeg.AVERROR_EOF)
break;
CheckRet();
Decode();
}
if (Ms.Length > 0)
{
se = new SoundEffect(Ms.ToArray(), 0, (int)Ms.Length, OutFrame->sample_rate, (AudioChannels)Channels, 0, 0);
//se.Duration; Stream->duration;
see = se.CreateInstance();
see.Play();
}
}
}
我发现C++ FFmpeg distorted sound when converting audio中的一些代码将其改编为c＃。在我的程序中慢慢尝试了一下它。结果我的解码器做错了。因此，重新采样或编码的所有尝试都将失败。
using FFmpeg.AutoGen;
using System;
using System.IO;
namespace ConsoleApp1
{
//adapted using code from https://stackoverflow.com/questions/32051847/c-ffmpeg-distorted-sound-when-converting-audio?rq=1
public unsafe class Program
{
public static AVStream* in_audioStream { get; private set; }
static unsafe void die(string str)
{
throw new Exception(str);
}
private static unsafe AVStream* add_audio_stream(AVFormatContext* oc, AVCodecID codec_id, int sample_rate = 44100)
{
AVCodecContext* c;
AVCodec* encoder = ffmpeg.avcodec_find_encoder(codec_id);
AVStream* st = ffmpeg.avformat_new_stream(oc, encoder);
if (st == null)
{
die("av_new_stream");
}
c = st->codec;
c->codec_id = codec_id;
c->codec_type = AVMediaType.AVMEDIA_TYPE_AUDIO;
/* put sample parameters */
c->bit_rate = 64000;
c->sample_rate = sample_rate;
c->channels = 2;
c->sample_fmt = encoder->sample_fmts[0];
c->channel_layout = ffmpeg.AV_CH_LAYOUT_STEREO;
// some formats want stream headers to be separate
if ((oc->oformat->flags & ffmpeg.AVFMT_GLOBALHEADER) != 0)
{
c->flags |= ffmpeg.AV_CODEC_FLAG_GLOBAL_HEADER;
}
return st;
}
private static unsafe void open_audio(AVFormatContext* oc, AVStream* st)
{
AVCodecContext* c = st->codec;
AVCodec* codec;
/* find the audio encoder */
codec = ffmpeg.avcodec_find_encoder(c->codec_id);
if (codec == null)
{
die("avcodec_find_encoder");
}
/* open it */
AVDictionary* dict = null;
ffmpeg.av_dict_set(&dict, "strict", "+experimental", 0);
int res = ffmpeg.avcodec_open2(c, codec, &dict);
if (res < 0)
{
die("avcodec_open");
}
}
public static int DecodeNext(AVCodecContext* avctx, AVFrame* frame, ref int got_frame_ptr, AVPacket* avpkt)
{
int ret = 0;
got_frame_ptr = 0;
if ((ret = ffmpeg.avcodec_receive_frame(avctx, frame)) == 0)
{
//0 on success, otherwise negative error code
got_frame_ptr = 1;
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EAGAIN))
{
//AVERROR(EAGAIN): input is not accepted in the current state - user must read output with avcodec_receive_packet()
//(once all output is read, the packet should be resent, and the call will not fail with EAGAIN)
ret = Decode(avctx, frame, ref got_frame_ptr, avpkt);
}
else if (ret == ffmpeg.AVERROR_EOF)
{
die("AVERROR_EOF: the encoder has been flushed, and no new frames can be sent to it");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EINVAL))
{
die("AVERROR(EINVAL): codec not opened, refcounted_frames not set, it is a decoder, or requires flush");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.ENOMEM))
{
die("Failed to add packet to internal queue, or similar other errors: legitimate decoding errors");
}
else
{
die("unknown");
}
return ret;
}
public static int Decode(AVCodecContext* avctx, AVFrame* frame, ref int got_frame_ptr, AVPacket* avpkt)
{
int ret = 0;
got_frame_ptr = 0;
if ((ret = ffmpeg.avcodec_send_packet(avctx, avpkt)) == 0)
{
//0 on success, otherwise negative error code
return DecodeNext(avctx, frame, ref got_frame_ptr, avpkt);
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EAGAIN))
{
die("input is not accepted in the current state - user must read output with avcodec_receive_frame()(once all output is read, the packet should be resent, and the call will not fail with EAGAIN");
}
else if (ret == ffmpeg.AVERROR_EOF)
{
die("AVERROR_EOF: the decoder has been flushed, and no new packets can be sent to it (also returned if more than 1 flush packet is sent");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EINVAL))
{
die("codec not opened, it is an encoder, or requires flush");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.ENOMEM))
{
die("Failed to add packet to internal queue, or similar other errors: legitimate decoding errors");
}
else
{
die("unknown");
}
return ret;//ffmpeg.avcodec_decode_audio4(fileCodecContext, audioFrameDecoded, &frameFinished, &inPacket);
}
public static int DecodeFlush(AVCodecContext* avctx, AVPacket* avpkt)
{
avpkt->data = null;
avpkt->size = 0;
return ffmpeg.avcodec_send_packet(avctx, avpkt);
}
public static int EncodeNext(AVCodecContext* avctx, AVPacket* avpkt, AVFrame* frame, ref int got_packet_ptr)
{
int ret = 0;
got_packet_ptr = 0;
if ((ret = ffmpeg.avcodec_receive_packet(avctx, avpkt)) == 0)
{
got_packet_ptr = 1;
//0 on success, otherwise negative error code
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EAGAIN))
{
//output is not available in the current state - user must try to send input
return Encode(avctx, avpkt, frame, ref got_packet_ptr);
}
else if (ret == ffmpeg.AVERROR_EOF)
{
die("AVERROR_EOF: the encoder has been fully flushed, and there will be no more output packets");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EINVAL))
{
die("AVERROR(EINVAL) codec not opened, or it is an encoder other errors: legitimate decoding errors");
}
else
{
die("unknown");
}
return ret;//ffmpeg.avcodec_encode_audio2(audioCodecContext, &outPacket, audioFrameConverted, &frameFinished)
}
public static int Encode(AVCodecContext* avctx, AVPacket* avpkt, AVFrame* frame, ref int got_packet_ptr)
{
int ret = 0;
got_packet_ptr = 0;
if ((ret = ffmpeg.avcodec_send_frame(avctx, frame)) == 0)
{
//0 on success, otherwise negative error code
return EncodeNext(avctx, avpkt, frame, ref got_packet_ptr);
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EAGAIN))
{
die("input is not accepted in the current state - user must read output with avcodec_receive_packet() (once all output is read, the packet should be resent, and the call will not fail with EAGAIN)");
}
else if (ret == ffmpeg.AVERROR_EOF)
{
die("AVERROR_EOF: the decoder has been flushed, and no new packets can be sent to it (also returned if more than 1 flush packet is sent");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.EINVAL))
{
die("AVERROR(ffmpeg.EINVAL) codec not opened, refcounted_frames not set, it is a decoder, or requires flush");
}
else if (ret == ffmpeg.AVERROR(ffmpeg.ENOMEM))
{
die("AVERROR(ENOMEM) failed to add packet to internal queue, or similar other errors: legitimate decoding errors");
}
else
{
die("unknown");
}
return ret;//ffmpeg.avcodec_encode_audio2(audioCodecContext, &outPacket, audioFrameConverted, &frameFinished)
}
public static int EncodeFlush(AVCodecContext* avctx)
{
return ffmpeg.avcodec_send_frame(avctx, null);
}
public static void Main(string[] argv)
{
//ffmpeg.av_register_all();
if (argv.Length != 2)
{
//fprintf(stderr, "%s <in> <out>\n", argv[0]);
return;
}
// Allocate and init re-usable frames
AVCodecContext* fileCodecContext, audioCodecContext;
AVFormatContext* formatContext, outContext;
AVStream* out_audioStream;
SwrContext* swrContext;
int streamId;
// input file
string file = argv[0];
int res = ffmpeg.avformat_open_input(&formatContext, file, null, null);
if (res != 0)
{
die("avformat_open_input");
}
res = ffmpeg.avformat_find_stream_info(formatContext, null);
if (res < 0)
{
die("avformat_find_stream_info");
}
AVCodec* codec;
res = ffmpeg.av_find_best_stream(formatContext, AVMediaType.AVMEDIA_TYPE_AUDIO, -1, -1, &codec, 0);
if (res < 0)
{
return; // die("av_find_best_stream");
}
streamId = res;
fileCodecContext = ffmpeg.avcodec_alloc_context3(codec);
AVCodecParameters* cp = null;
ffmpeg.avcodec_parameters_to_context(fileCodecContext, formatContext->streams[streamId]->codecpar);
res = ffmpeg.avcodec_open2(fileCodecContext, codec, null);
if (res < 0)
{
die("avcodec_open2");
}
in_audioStream = formatContext->streams[streamId];
// output file
//string outfile = Path.Combine(Path.GetTempPath(), $"{Path.GetFileNameWithoutExtension(argv[0])}.pcm");
//AVOutputFormat* fmt = fmt = ffmpeg.av_guess_format("s16le", null, null);
string outfile = argv[1];
AVOutputFormat * fmt = fmt = ffmpeg.av_guess_format(null, outfile, null);
if (fmt == null)
{
die("av_guess_format");
}
outContext = ffmpeg.avformat_alloc_context();
outContext->oformat = fmt;
out_audioStream = add_audio_stream(outContext, fmt->audio_codec, in_audioStream->codec->sample_rate);
open_audio(outContext, out_audioStream);
out_audioStream->time_base = in_audioStream->time_base;
res = ffmpeg.avio_open2(&outContext->pb, outfile, ffmpeg.AVIO_FLAG_WRITE, null, null);
if (res < 0)
{
die("url_fopen");
}
ffmpeg.avformat_write_header(outContext, null);
AVCodec* ocodec;
res = ffmpeg.av_find_best_stream(outContext, AVMediaType.AVMEDIA_TYPE_AUDIO, -1, -1, &ocodec, 0);
audioCodecContext = ffmpeg.avcodec_alloc_context3(ocodec);
ffmpeg.avcodec_parameters_to_context(audioCodecContext, out_audioStream->codecpar);
res = ffmpeg.avcodec_open2(audioCodecContext, ocodec, null);
if (res < 0)
{
die("avcodec_open2");
}
// resampling
swrContext = ffmpeg.swr_alloc();
ffmpeg.av_opt_set_channel_layout(swrContext, "in_channel_layout", (long)fileCodecContext->channel_layout, 0);
ffmpeg.av_opt_set_channel_layout(swrContext, "out_channel_layout", (long)audioCodecContext->channel_layout, 0);
ffmpeg.av_opt_set_int(swrContext, "in_sample_rate", fileCodecContext->sample_rate, 0);
ffmpeg.av_opt_set_int(swrContext, "out_sample_rate", audioCodecContext->sample_rate, 0);
ffmpeg.av_opt_set_sample_fmt(swrContext, "in_sample_fmt", fileCodecContext->sample_fmt, 0);
ffmpeg.av_opt_set_sample_fmt(swrContext, "out_sample_fmt", audioCodecContext->sample_fmt, 0);
res = ffmpeg.swr_init(swrContext);
if (res < 0)
{
die("swr_init");
}
AVFrame* audioFrameDecoded = ffmpeg.av_frame_alloc();
if (audioFrameDecoded == null)
{
die("Could not allocate audio frame");
}
audioFrameDecoded->format = (int)fileCodecContext->sample_fmt;
audioFrameDecoded->channel_layout = fileCodecContext->channel_layout;
audioFrameDecoded->channels = fileCodecContext->channels;
audioFrameDecoded->sample_rate = fileCodecContext->sample_rate;
AVFrame* audioFrameConverted = ffmpeg.av_frame_alloc();
if (audioFrameConverted == null)
{
die("Could not allocate audio frame");
}
audioFrameConverted->nb_samples = audioCodecContext->frame_size;
audioFrameConverted->format = (int)audioCodecContext->sample_fmt;
audioFrameConverted->channel_layout = audioCodecContext->channel_layout;
audioFrameConverted->channels = audioCodecContext->channels;
audioFrameConverted->sample_rate = audioCodecContext->sample_rate;
if (audioFrameConverted->nb_samples <= 0)
{
audioFrameConverted->nb_samples = 32;
}
AVPacket inPacket;
ffmpeg.av_init_packet(&inPacket);
inPacket.data = null;
inPacket.size = 0;
int frameFinished = 0;
for (; ; )
{
if (ffmpeg.av_read_frame(formatContext, &inPacket) < 0)
{
break;
}
if (inPacket.stream_index == streamId)
{
int len = Decode(fileCodecContext, audioFrameDecoded, ref frameFinished, &inPacket);
if (len == ffmpeg.AVERROR_EOF)
{
break;
}
if (frameFinished != 0)
{
// Convert
byte* convertedData = null;
if (ffmpeg.av_samples_alloc(&convertedData,
null,
audioCodecContext->channels,
audioFrameConverted->nb_samples,
audioCodecContext->sample_fmt, 0) < 0)
{
die("Could not allocate samples");
}
int outSamples = 0;
fixed (byte** tmp = (byte*[])audioFrameDecoded->data)
{
outSamples = ffmpeg.swr_convert(swrContext, null, 0,
//&convertedData,
//audioFrameConverted->nb_samples,
tmp,
audioFrameDecoded->nb_samples);
}
if (outSamples < 0)
{
die("Could not convert");
}
for (; ; )
{
outSamples = ffmpeg.swr_get_out_samples(swrContext, 0);
if ((outSamples < audioCodecContext->frame_size * audioCodecContext->channels) || audioCodecContext->frame_size == 0 && (outSamples < audioFrameConverted->nb_samples * audioCodecContext->channels))
{
break; // see comments, thanks to @dajuric for fixing this
}
outSamples = ffmpeg.swr_convert(swrContext,
&convertedData,
audioFrameConverted->nb_samples, null, 0);
int buffer_size = ffmpeg.av_samples_get_buffer_size(null,
audioCodecContext->channels,
audioFrameConverted->nb_samples,
audioCodecContext->sample_fmt,
0);
if (buffer_size < 0)
{
die("Invalid buffer size");
}
if (ffmpeg.avcodec_fill_audio_frame(audioFrameConverted,
audioCodecContext->channels,
audioCodecContext->sample_fmt,
convertedData,
buffer_size,
0) < 0)
{
die("Could not fill frame");
}
AVPacket outPacket;
ffmpeg.av_init_packet(&outPacket);
outPacket.data = null;
outPacket.size = 0;
if (Encode(audioCodecContext, &outPacket, audioFrameConverted, ref frameFinished) < 0)
{
die("Error encoding audio frame");
}
//outPacket.flags |= ffmpeg.AV_PKT_FLAG_KEY;
outPacket.stream_index = out_audioStream->index;
//outPacket.data = audio_outbuf;
outPacket.dts = audioFrameDecoded->pkt_dts;
outPacket.pts = audioFrameDecoded->pkt_pts;
ffmpeg.av_packet_rescale_ts(&outPacket, in_audioStream->time_base, out_audioStream->time_base);
if (frameFinished != 0)
{
if (ffmpeg.av_interleaved_write_frame(outContext, &outPacket) != 0)
{
die("Error while writing audio frame");
}
ffmpeg.av_packet_unref(&outPacket);
}
}
}
}
}
EncodeFlush(audioCodecContext);
DecodeFlush(fileCodecContext, &inPacket);
ffmpeg.swr_close(swrContext);
ffmpeg.swr_free(&swrContext);
ffmpeg.av_frame_free(&audioFrameConverted);
ffmpeg.av_frame_free(&audioFrameDecoded);
ffmpeg.av_packet_unref(&inPacket);
ffmpeg.av_write_trailer(outContext);
ffmpeg.avio_close(outContext->pb);
ffmpeg.avcodec_close(fileCodecContext);
ffmpeg.avcodec_free_context(&fileCodecContext);
ffmpeg.avformat_close_input(&formatContext);
return;
}
}
}